diff --git a/app/db/tables.ts b/app/db/tables.ts
index 23d734911..8a91c86c5 100644
--- a/app/db/tables.ts
+++ b/app/db/tables.ts
@@ -866,6 +866,43 @@ export interface TournamentTeamMember {
 	isLooking: Generated<DBBoolean>;
 }
 
+/** Stable shadow of a tournament team's identity that survives the team's hard-deletion, so the audit log can still resolve its name. */
+export interface TournamentTeamHistory {
+	// xxx: maybe we need soft delete instead. it's possible the same id gets reused... alternative TournamentTeamHistory has its own tournamentTeamId that TournamentAuditLog refers to (also keep tournamentTeamId)
+	/** Mirrors the original `TournamentTeam.id`. Not a live foreign key so it is not cascade-deleted with the team. */
+	tournamentTeamId: number;
+	tournamentId: number;
+	name: string;
+}
+
+export const TOURNAMENT_AUDIT_LOG_TYPES = [
+	"MEMBER_ADDED",
+	"MEMBER_REMOVED",
+	"TEAM_REGISTERED",
+	"TEAM_UNREGISTERED",
+	"TEAM_CHECKED_IN",
+	"TEAM_CHECKED_OUT",
+	"TEAM_DROPPED_OUT",
+	"TEAM_DROP_OUT_UNDONE",
+] as const;
+
+export interface TournamentAuditLog {
+	id: GeneratedAlways<number>;
+	tournamentId: number;
+	type: (typeof TOURNAMENT_AUDIT_LOG_TYPES)[number];
+	/** The user who performed the action. */
+	actorUserId: number;
+	/** The affected member, for member-level events. `null` for team-level events. */
+	subjectUserId: number | null;
+	tournamentTeamId: number | null;
+	metadata: JSONColumnTypeNullable<TournamentAuditLogMetadata>;
+	createdAt: number;
+}
+
+export interface TournamentAuditLogMetadata {
+	bracketIdx?: number;
+}
+
 export interface TournamentOrganization {
 	id: GeneratedAlways<number>;
 	name: string;
@@ -1436,6 +1473,8 @@ export interface DB {
 	TournamentTeam: TournamentTeam;
 	TournamentTeamCheckIn: TournamentTeamCheckIn;
 	TournamentTeamMember: TournamentTeamMember;
+	TournamentTeamHistory: TournamentTeamHistory;
+	TournamentAuditLog: TournamentAuditLog;
 	TournamentOrganization: TournamentOrganization;
 	TournamentOrganizationMember: TournamentOrganizationMember;
 	TournamentOrganizationBadge: TournamentOrganizationBadge;
diff --git a/app/features/tournament-bracket/actions/to.$id.brackets.server.ts b/app/features/tournament-bracket/actions/to.$id.brackets.server.ts
index ef451c4cf..956a6fc98 100644
--- a/app/features/tournament-bracket/actions/to.$id.brackets.server.ts
+++ b/app/features/tournament-bracket/actions/to.$id.brackets.server.ts
@@ -299,6 +299,7 @@ export const action: ActionFunction = async ({ params, request }) => {
 			);
 
 			await TournamentTeamRepository.checkIn(teamMemberOf.id, {
+				actorUserId: user.id,
 				bracketIdx: data.bracketIdx,
 			});
 
diff --git a/app/features/tournament/TournamentAuditLogRepository.server.test.ts b/app/features/tournament/TournamentAuditLogRepository.server.test.ts
new file mode 100644
index 000000000..8a0c9fe0a
--- /dev/null
+++ b/app/features/tournament/TournamentAuditLogRepository.server.test.ts
@@ -0,0 +1,240 @@
+import { afterEach, beforeEach, describe, expect, test } from "vitest";
+import { db } from "~/db/sql";
+import type { Tables } from "~/db/tables";
+import { dbInsertUsers, dbReset } from "~/utils/Test";
+import * as TournamentAuditLogRepository from "./TournamentAuditLogRepository.server";
+
+const createTournament = () =>
+	db
+		.insertInto("Tournament")
+		.values({
+			mapPickingStyle: "TO",
+			settings: JSON.stringify({ bracketProgression: [] }),
+		})
+		.returning("id")
+		.executeTakeFirstOrThrow();
+
+const createTeam = (tournamentId: number, name: string) =>
+	db
+		.insertInto("TournamentTeam")
+		.values({
+			tournamentId,
+			name,
+			inviteCode: `inv-${tournamentId}-${name}`,
+		})
+		.returning("id")
+		.executeTakeFirstOrThrow();
+
+const insertEvent = (args: {
+	type: Tables["TournamentAuditLog"]["type"];
+	actorUserId: number;
+	tournamentTeamId: number;
+	subjectUserId?: number;
+	metadata?: { bracketIdx?: number };
+}) =>
+	db
+		.transaction()
+		.execute((trx) => TournamentAuditLogRepository.insert(trx, args));
+
+describe("TournamentAuditLogRepository", () => {
+	beforeEach(async () => {
+		await dbInsertUsers(3);
+	});
+
+	afterEach(() => {
+		dbReset();
+	});
+
+	test("insert creates a stable history row from the live team", async () => {
+		const tournament = await createTournament();
+		const team = await createTeam(tournament.id, "Team Olive");
+
+		await insertEvent({
+			type: "TEAM_REGISTERED",
+			actorUserId: 1,
+			tournamentTeamId: team.id,
+		});
+
+		const teams = await TournamentAuditLogRepository.findTeamsByTournamentId(
+			tournament.id,
+		);
+
+		expect(teams).toHaveLength(1);
+		expect(teams[0].id).toBe(team.id);
+		expect(teams[0].name).toBe("Team Olive");
+	});
+
+	test("findByTournamentId returns events newest first with resolved relations", async () => {
+		const tournament = await createTournament();
+		const team = await createTeam(tournament.id, "Team Olive");
+
+		await insertEvent({
+			type: "TEAM_REGISTERED",
+			actorUserId: 1,
+			tournamentTeamId: team.id,
+			subjectUserId: 1,
+		});
+		await insertEvent({
+			type: "MEMBER_ADDED",
+			actorUserId: 1,
+			tournamentTeamId: team.id,
+			subjectUserId: 2,
+		});
+
+		const events = await TournamentAuditLogRepository.findByTournamentId({
+			tournamentId: tournament.id,
+			limit: 30,
+			offset: 0,
+		});
+
+		expect(events).toHaveLength(2);
+		// newest first
+		expect(events[0].type).toBe("MEMBER_ADDED");
+		expect(events[0].actor?.id).toBe(1);
+		expect(events[0].subject?.id).toBe(2);
+		expect(events[0].team?.name).toBe("Team Olive");
+		expect(events[1].type).toBe("TEAM_REGISTERED");
+	});
+
+	test("team name survives the team being deleted", async () => {
+		const tournament = await createTournament();
+		const team = await createTeam(tournament.id, "Team Olive");
+
+		await insertEvent({
+			type: "TEAM_UNREGISTERED",
+			actorUserId: 1,
+			tournamentTeamId: team.id,
+		});
+
+		await db
+			.deleteFrom("TournamentTeam")
+			.where("TournamentTeam.id", "=", team.id)
+			.execute();
+
+		const events = await TournamentAuditLogRepository.findByTournamentId({
+			tournamentId: tournament.id,
+			limit: 30,
+			offset: 0,
+		});
+
+		expect(events).toHaveLength(1);
+		expect(events[0].team?.name).toBe("Team Olive");
+	});
+
+	test("filters by event type and by team", async () => {
+		const tournament = await createTournament();
+		const teamA = await createTeam(tournament.id, "Team A");
+		const teamB = await createTeam(tournament.id, "Team B");
+
+		await insertEvent({
+			type: "TEAM_REGISTERED",
+			actorUserId: 1,
+			tournamentTeamId: teamA.id,
+		});
+		await insertEvent({
+			type: "TEAM_CHECKED_IN",
+			actorUserId: 1,
+			tournamentTeamId: teamA.id,
+		});
+		await insertEvent({
+			type: "TEAM_REGISTERED",
+			actorUserId: 1,
+			tournamentTeamId: teamB.id,
+		});
+
+		const byType = await TournamentAuditLogRepository.findByTournamentId({
+			tournamentId: tournament.id,
+			type: "TEAM_REGISTERED",
+			limit: 30,
+			offset: 0,
+		});
+		expect(byType).toHaveLength(2);
+
+		const byTeam = await TournamentAuditLogRepository.findByTournamentId({
+			tournamentId: tournament.id,
+			tournamentTeamId: teamA.id,
+			limit: 30,
+			offset: 0,
+		});
+		expect(byTeam).toHaveLength(2);
+
+		const count = await TournamentAuditLogRepository.countByTournamentId({
+			tournamentId: tournament.id,
+			type: "TEAM_REGISTERED",
+		});
+		expect(count).toBe(2);
+	});
+
+	test("paginates via limit and offset", async () => {
+		const tournament = await createTournament();
+		const team = await createTeam(tournament.id, "Team Olive");
+
+		for (let i = 0; i < 3; i++) {
+			await insertEvent({
+				type: "TEAM_CHECKED_IN",
+				actorUserId: 1,
+				tournamentTeamId: team.id,
+			});
+		}
+
+		const firstPage = await TournamentAuditLogRepository.findByTournamentId({
+			tournamentId: tournament.id,
+			limit: 2,
+			offset: 0,
+		});
+		const secondPage = await TournamentAuditLogRepository.findByTournamentId({
+			tournamentId: tournament.id,
+			limit: 2,
+			offset: 2,
+		});
+
+		expect(firstPage).toHaveLength(2);
+		expect(secondPage).toHaveLength(1);
+	});
+
+	test("stores and reads back metadata", async () => {
+		const tournament = await createTournament();
+		const team = await createTeam(tournament.id, "Team Olive");
+
+		await insertEvent({
+			type: "TEAM_CHECKED_IN",
+			actorUserId: 1,
+			tournamentTeamId: team.id,
+			metadata: { bracketIdx: 2 },
+		});
+
+		const events = await TournamentAuditLogRepository.findByTournamentId({
+			tournamentId: tournament.id,
+			limit: 30,
+			offset: 0,
+		});
+
+		expect(events[0].metadata?.bracketIdx).toBe(2);
+	});
+
+	test("updateTeamHistoryName keeps the preserved name current", async () => {
+		const tournament = await createTournament();
+		const team = await createTeam(tournament.id, "Old Name");
+
+		await insertEvent({
+			type: "TEAM_REGISTERED",
+			actorUserId: 1,
+			tournamentTeamId: team.id,
+		});
+
+		await db.transaction().execute((trx) =>
+			TournamentAuditLogRepository.updateTeamHistoryName(trx, {
+				tournamentTeamId: team.id,
+				name: "New Name",
+			}),
+		);
+
+		const events = await TournamentAuditLogRepository.findByTournamentId({
+			tournamentId: tournament.id,
+			limit: 30,
+			offset: 0,
+		});
+
+		expect(events[0].team?.name).toBe("New Name");
+	});
+});
diff --git a/app/features/tournament/TournamentAuditLogRepository.server.ts b/app/features/tournament/TournamentAuditLogRepository.server.ts
new file mode 100644
index 000000000..78e3d28ed
--- /dev/null
+++ b/app/features/tournament/TournamentAuditLogRepository.server.ts
@@ -0,0 +1,196 @@
+import type { Transaction } from "kysely";
+import { jsonObjectFrom } from "kysely/helpers/sqlite";
+import { db } from "~/db/sql";
+import type { DB, Tables, TournamentAuditLogMetadata } from "~/db/tables";
+import { databaseTimestampNow } from "~/utils/dates";
+import { COMMON_USER_FIELDS } from "~/utils/kysely.server";
+
+export const AUDIT_LOG_PAGE_SIZE = 30;
+
+type TournamentAuditLogType = Tables["TournamentAuditLog"]["type"];
+
+// xxx: can we use TablesInsertable + Pick
+interface InsertArgs {
+	type: TournamentAuditLogType;
+	/** The user who performed the action. */
+	actorUserId: number;
+	/** The team the event concerns. Its identity is preserved in `TournamentTeamHistory`. */
+	tournamentTeamId: number;
+	/** The affected member, for member-level events. */
+	subjectUserId?: number | null;
+	metadata?: TournamentAuditLogMetadata | null;
+}
+
+/**
+ * Inserts an audit log event within the caller's transaction (so it commits or
+ * rolls back atomically with the mutation it records). Ensures a stable
+ * `TournamentTeamHistory` row exists for the team, so the event remains readable
+ * even after the team is hard-deleted.
+ */
+export async function insert(trx: Transaction<DB>, args: InsertArgs) { // xxx: audit codebase, trx as second arg?
+	await trx
+		.insertInto("TournamentTeamHistory")
+		.columns(["tournamentTeamId", "tournamentId", "name"])
+		.expression((eb) =>
+			eb
+				.selectFrom("TournamentTeam")
+				.select([
+					"TournamentTeam.id",
+					"TournamentTeam.tournamentId",
+					"TournamentTeam.name",
+				])
+				.where("TournamentTeam.id", "=", args.tournamentTeamId),
+		)
+		.onConflict((oc) => oc.column("tournamentTeamId").doNothing())
+		.execute();
+
+	const { tournamentId } = await trx
+		.selectFrom("TournamentTeamHistory")
+		.select("TournamentTeamHistory.tournamentId")
+		.where("TournamentTeamHistory.tournamentTeamId", "=", args.tournamentTeamId)
+		.executeTakeFirstOrThrow();
+
+	await trx
+		.insertInto("TournamentAuditLog")
+		.values({
+			tournamentId,
+			type: args.type,
+			actorUserId: args.actorUserId,
+			subjectUserId: args.subjectUserId ?? null,
+			tournamentTeamId: args.tournamentTeamId,
+			metadata: args.metadata ? JSON.stringify(args.metadata) : null,
+			createdAt: databaseTimestampNow(),
+		})
+		.execute();
+}
+
+/**
+ * Keeps the team's preserved name current after a rename. No-op when the team
+ * has no history row yet (it will be created with the up-to-date name on its
+ * first audited event).
+ */
+export function updateTeamHistoryName(
+	trx: Transaction<DB>,
+	{ tournamentTeamId, name }: { tournamentTeamId: number; name: string },
+) {
+	return trx
+		.updateTable("TournamentTeamHistory")
+		.set({ name })
+		.where("TournamentTeamHistory.tournamentTeamId", "=", tournamentTeamId)
+		.execute();
+}
+
+/**
+ * Returns a page of audit log events for a tournament, newest first, optionally
+ * filtered by event type and/or team. Resolves the actor, the affected member
+ * (when present) and the team name (preserved even for deleted teams).
+ */
+export function findByTournamentId({
+	tournamentId,
+	type,
+	tournamentTeamId,
+	limit,
+	offset,
+}: {
+	tournamentId: number;
+	type?: TournamentAuditLogType;
+	tournamentTeamId?: number;
+	limit: number;
+	offset: number;
+}) {
+	let query = db
+		.selectFrom("TournamentAuditLog")
+		.select((eb) => [
+			"TournamentAuditLog.id",
+			"TournamentAuditLog.type",
+			"TournamentAuditLog.createdAt",
+			"TournamentAuditLog.metadata",
+			jsonObjectFrom(
+				eb
+					.selectFrom("User")
+					.select(COMMON_USER_FIELDS)
+					.whereRef("User.id", "=", "TournamentAuditLog.actorUserId"),
+			).as("actor"),
+			jsonObjectFrom(
+				eb
+					.selectFrom("User")
+					.select(COMMON_USER_FIELDS)
+					.whereRef("User.id", "=", "TournamentAuditLog.subjectUserId"),
+			).as("subject"),
+			jsonObjectFrom(
+				eb
+					.selectFrom("TournamentTeamHistory")
+					.select([
+						"TournamentTeamHistory.tournamentTeamId as id",
+						"TournamentTeamHistory.name",
+					])
+					.whereRef(
+						"TournamentTeamHistory.tournamentTeamId",
+						"=",
+						"TournamentAuditLog.tournamentTeamId",
+					),
+			).as("team"),
+		])
+		.where("TournamentAuditLog.tournamentId", "=", tournamentId)
+		.orderBy("TournamentAuditLog.createdAt", "desc")
+		.orderBy("TournamentAuditLog.id", "desc")
+		.limit(limit)
+		.offset(offset);
+
+	if (type) {
+		query = query.where("TournamentAuditLog.type", "=", type);
+	}
+	if (typeof tournamentTeamId === "number") {
+		query = query.where(
+			"TournamentAuditLog.tournamentTeamId",
+			"=",
+			tournamentTeamId,
+		);
+	}
+
+	return query.execute();
+}
+
+/** Counts audit log events for a tournament matching the same optional filters as {@link findByTournamentId}. Used for pagination. */
+export async function countByTournamentId({
+	tournamentId,
+	type,
+	tournamentTeamId,
+}: {
+	tournamentId: number;
+	type?: TournamentAuditLogType;
+	tournamentTeamId?: number;
+}) {
+	let query = db
+		.selectFrom("TournamentAuditLog")
+		.select((eb) => eb.fn.countAll<number>().as("count"))
+		.where("TournamentAuditLog.tournamentId", "=", tournamentId);
+
+	if (type) {
+		query = query.where("TournamentAuditLog.type", "=", type);
+	}
+	if (typeof tournamentTeamId === "number") {
+		query = query.where(
+			"TournamentAuditLog.tournamentTeamId",
+			"=",
+			tournamentTeamId,
+		);
+	}
+
+	const result = await query.executeTakeFirstOrThrow();
+
+	return result.count;
+}
+
+/** Returns every team (including deleted ones) that has appeared in the tournament's audit log, for the team filter dropdown. */
+export function findTeamsByTournamentId(tournamentId: number) {
+	return db
+		.selectFrom("TournamentTeamHistory")
+		.select([
+			"TournamentTeamHistory.tournamentTeamId as id",
+			"TournamentTeamHistory.name",
+		])
+		.where("TournamentTeamHistory.tournamentId", "=", tournamentId)
+		.orderBy("TournamentTeamHistory.name", "asc")
+		.execute();
+}
diff --git a/app/features/tournament/TournamentTeamRepository.server.ts b/app/features/tournament/TournamentTeamRepository.server.ts
index 64458bc1c..b9e8caefd 100644
--- a/app/features/tournament/TournamentTeamRepository.server.ts
+++ b/app/features/tournament/TournamentTeamRepository.server.ts
@@ -8,6 +8,7 @@ import { flatZip } from "~/utils/arrays";
 import { databaseTimestampNow, dateToDatabaseTimestamp } from "~/utils/dates";
 import { shortNanoid } from "~/utils/id";
 import invariant from "~/utils/invariant";
+import * as TournamentAuditLogRepository from "./TournamentAuditLogRepository.server";
 
 export function setActiveRoster({
 	teamId,
@@ -111,11 +112,15 @@ export function create({
 	team,
 	avatarFileName,
 	userId,
+	actorUserId,
 	tournamentId,
 }: {
 	team: Pick<Tables["TournamentTeam"], "name" | "prefersNotToHost" | "teamId">;
 	avatarFileName?: string;
+	/** The user who becomes the team owner. */
 	userId: number;
+	/** The user performing the registration (differs from `userId` when an organizer registers a team for someone). */
+	actorUserId: number;
 	tournamentId: number;
 }) {
 	return db.transaction().execute(async (trx) => {
@@ -152,6 +157,13 @@ export function create({
 			})
 			.execute();
 
+		await TournamentAuditLogRepository.insert(trx, {
+			type: "TEAM_REGISTERED",
+			actorUserId,
+			tournamentTeamId: tournamentTeam.id,
+			subjectUserId: userId,
+		});
+
 		return tournamentTeam;
 	});
 }
@@ -317,6 +329,11 @@ export function update({
 			})
 			.where("TournamentTeam.id", "=", team.id)
 			.execute();
+
+		await TournamentAuditLogRepository.updateTeamHistoryName(trx, {
+			tournamentTeamId: team.id,
+			name: team.name,
+		});
 	});
 }
 
@@ -416,9 +433,9 @@ export function updateAbDivisions(
  */
 export function checkIn(
 	tournamentTeamId: number,
-	options?: { bracketIdx: number },
+	options: { actorUserId: number; bracketIdx?: number },
 ) {
-	const bracketIdx = options?.bracketIdx ?? null;
+	const bracketIdx = options.bracketIdx ?? null;
 
 	return db.transaction().execute(async (trx) => {
 		let query = trx
@@ -446,15 +463,24 @@ export function checkIn(
 				bracketIdx,
 			})
 			.execute();
+
+		await TournamentAuditLogRepository.insert(trx, {
+			type: "TEAM_CHECKED_IN",
+			actorUserId: options.actorUserId,
+			tournamentTeamId,
+			metadata: typeof bracketIdx === "number" ? { bracketIdx } : null,
+		});
 	});
 }
 
 export function checkOut({
 	tournamentTeamId,
 	bracketIdx,
+	actorUserId,
 }: {
 	tournamentTeamId: number;
 	bracketIdx: number | null;
+	actorUserId: number;
 }) {
 	return db.transaction().execute(async (trx) => {
 		let query = trx
@@ -478,6 +504,13 @@ export function checkOut({
 				})
 				.execute();
 		}
+
+		await TournamentAuditLogRepository.insert(trx, {
+			type: "TEAM_CHECKED_OUT",
+			actorUserId,
+			tournamentTeamId,
+			metadata: typeof bracketIdx === "number" ? { bracketIdx } : null,
+		});
 	});
 }
 
@@ -488,21 +521,30 @@ export function updateName({
 	tournamentTeamId: number;
 	name: string;
 }) {
-	return db
-		.updateTable("TournamentTeam")
-		.set({
+	return db.transaction().execute(async (trx) => {
+		await trx
+			.updateTable("TournamentTeam")
+			.set({
+				name,
+			})
+			.where("id", "=", tournamentTeamId)
+			.execute();
+
+		await TournamentAuditLogRepository.updateTeamHistoryName(trx, {
+			tournamentTeamId,
 			name,
-		})
-		.where("id", "=", tournamentTeamId)
-		.execute();
+		});
+	});
 }
 
 export function dropOut({
 	tournamentTeamId,
 	previewBracketIdxs,
+	actorUserId,
 }: {
 	tournamentTeamId: number;
 	previewBracketIdxs: number[];
+	actorUserId: number;
 }) {
 	return db.transaction().execute(async (trx) => {
 		await trx
@@ -518,17 +560,34 @@ export function dropOut({
 			})
 			.where("id", "=", tournamentTeamId)
 			.execute();
+
+		await TournamentAuditLogRepository.insert(trx, {
+			type: "TEAM_DROPPED_OUT",
+			actorUserId,
+			tournamentTeamId,
+		});
 	});
 }
 
-export function undoDropOut(tournamentTeamId: number) {
-	return db
-		.updateTable("TournamentTeam")
-		.set({
-			droppedOut: 0,
-		})
-		.where("id", "=", tournamentTeamId)
-		.execute();
+export function undoDropOut(
+	tournamentTeamId: number,
+	{ actorUserId }: { actorUserId: number },
+) {
+	return db.transaction().execute(async (trx) => {
+		await trx
+			.updateTable("TournamentTeam")
+			.set({
+				droppedOut: 0,
+			})
+			.where("id", "=", tournamentTeamId)
+			.execute();
+
+		await TournamentAuditLogRepository.insert(trx, {
+			type: "TEAM_DROP_OUT_UNDONE",
+			actorUserId,
+			tournamentTeamId,
+		});
+	});
 }
 
 export function join({
@@ -536,21 +595,36 @@ export function join({
 	whatToDoWithPreviousTeam,
 	newTeamId,
 	userId,
+	actorUserId,
 	checkOutTeam = false,
 }: {
 	previousTeamId?: number;
 	whatToDoWithPreviousTeam?: "LEAVE" | "DELETE";
 	newTeamId: number;
+	/** The user joining the team. */
 	userId: number;
+	/** The user performing the action (differs from `userId` when an owner or organizer adds someone). */
+	actorUserId: number;
 	checkOutTeam?: boolean;
 }) {
 	return db.transaction().execute(async (trx) => {
 		if (whatToDoWithPreviousTeam === "DELETE") {
+			await TournamentAuditLogRepository.insert(trx, {
+				type: "TEAM_UNREGISTERED",
+				actorUserId,
+				tournamentTeamId: previousTeamId!,
+			});
 			await trx
 				.deleteFrom("TournamentTeam")
 				.where("TournamentTeam.id", "=", previousTeamId!)
 				.execute();
 		} else if (whatToDoWithPreviousTeam === "LEAVE") {
+			await TournamentAuditLogRepository.insert(trx, {
+				type: "MEMBER_REMOVED",
+				actorUserId,
+				tournamentTeamId: previousTeamId!,
+				subjectUserId: userId,
+			});
 			await trx
 				.deleteFrom("TournamentTeamMember")
 				.where("TournamentTeamMember.tournamentTeamId", "=", previousTeamId!)
@@ -587,11 +661,27 @@ export function join({
 				inGameName,
 			})
 			.execute();
+
+		await TournamentAuditLogRepository.insert(trx, {
+			type: "MEMBER_ADDED",
+			actorUserId,
+			tournamentTeamId: newTeamId,
+			subjectUserId: userId,
+		});
 	});
 }
 
-export function del(tournamentTeamId: number) {
+export function del(
+	tournamentTeamId: number,
+	{ actorUserId }: { actorUserId: number },
+) {
 	return db.transaction().execute(async (trx) => {
+		await TournamentAuditLogRepository.insert(trx, {
+			type: "TEAM_UNREGISTERED",
+			actorUserId,
+			tournamentTeamId,
+		});
+
 		await trx
 			.deleteFrom("MapPoolMap")
 			.where("MapPoolMap.tournamentTeamId", "=", tournamentTeamId)
@@ -604,12 +694,31 @@ export function del(tournamentTeamId: number) {
 	});
 }
 
-export function leave({ teamId, userId }: { teamId: number; userId: number }) {
-	return db
-		.deleteFrom("TournamentTeamMember")
-		.where("TournamentTeamMember.tournamentTeamId", "=", teamId)
-		.where("TournamentTeamMember.userId", "=", userId)
-		.execute();
+export function leave({
+	teamId,
+	userId,
+	actorUserId,
+}: {
+	teamId: number;
+	/** The member leaving the team. */
+	userId: number;
+	/** The user performing the action (differs from `userId` when an owner or organizer removes someone). */
+	actorUserId: number;
+}) {
+	return db.transaction().execute(async (trx) => {
+		await TournamentAuditLogRepository.insert(trx, {
+			type: "MEMBER_REMOVED",
+			actorUserId,
+			tournamentTeamId: teamId,
+			subjectUserId: userId,
+		});
+
+		await trx
+			.deleteFrom("TournamentTeamMember")
+			.where("TournamentTeamMember.tournamentTeamId", "=", teamId)
+			.where("TournamentTeamMember.userId", "=", userId)
+			.execute();
+	});
 }
 
 export function transferOwnership(
diff --git a/app/features/tournament/actions/to.$id.admin.server.ts b/app/features/tournament/actions/to.$id.admin.server.ts
index 76ac9ce98..2e1e13411 100644
--- a/app/features/tournament/actions/to.$id.admin.server.ts
+++ b/app/features/tournament/actions/to.$id.admin.server.ts
@@ -76,6 +76,7 @@ export const action: ActionFunction = async ({ request, params }) => {
 					teamId: null,
 				},
 				userId: data.userId,
+				actorUserId: user.id,
 				tournamentId,
 			});
 			await TournamentLFGRepository.leaveLfg({
@@ -141,11 +142,11 @@ export const action: ActionFunction = async ({ request, params }) => {
 			invariant(bracket, "Invalid bracket idx");
 			errorToastIfFalsy(bracket.preview, "Bracket has been started");
 
-			await TournamentTeamRepository.checkIn(
-				data.teamId,
+			await TournamentTeamRepository.checkIn(data.teamId, {
+				actorUserId: user.id,
 				// no sources = regular check in
-				bracket.sources ? { bracketIdx: data.bracketIdx } : undefined,
-			);
+				bracketIdx: bracket.sources ? data.bracketIdx : undefined,
+			});
 
 			message = "Checked team in";
 			break;
@@ -165,6 +166,7 @@ export const action: ActionFunction = async ({ request, params }) => {
 
 			await TournamentTeamRepository.checkOut({
 				tournamentTeamId: data.teamId,
+				actorUserId: user.id,
 				// no sources = regular check in
 				bracketIdx: !bracket.sources ? null : data.bracketIdx,
 			});
@@ -206,6 +208,7 @@ export const action: ActionFunction = async ({ request, params }) => {
 			await TournamentTeamRepository.leave({
 				userId: data.memberId,
 				teamId: team.id,
+				actorUserId: user.id,
 			});
 
 			ShowcaseTournaments.removeFromCached({
@@ -256,6 +259,7 @@ export const action: ActionFunction = async ({ request, params }) => {
 			});
 			await TournamentTeamRepository.join({
 				userId: data.userId,
+				actorUserId: user.id,
 				newTeamId: team.id,
 				previousTeamId: previousTeam?.id,
 				// this team is not checked in & tournament started, so we can simply delete it
@@ -300,7 +304,7 @@ export const action: ActionFunction = async ({ request, params }) => {
 			errorToastIfFalsy(team, "Invalid team id");
 			errorToastIfFalsy(!tournament.hasStarted, "Tournament has started");
 
-			await TournamentTeamRepository.del(team.id);
+			await TournamentTeamRepository.del(team.id, { actorUserId: user.id });
 
 			for (const member of team.members) {
 				ShowcaseTournaments.removeFromCached({
@@ -399,6 +403,7 @@ export const action: ActionFunction = async ({ request, params }) => {
 
 			await TournamentTeamRepository.dropOut({
 				tournamentTeamId: data.teamId,
+				actorUserId: user.id,
 				previewBracketIdxs: tournament.brackets.flatMap((b, idx) =>
 					b.preview ? idx : [],
 				),
@@ -427,7 +432,9 @@ export const action: ActionFunction = async ({ request, params }) => {
 		case "UNDO_DROP_TEAM_OUT": {
 			validateIsTournamentOrganizer();
 
-			await TournamentTeamRepository.undoDropOut(data.teamId);
+			await TournamentTeamRepository.undoDropOut(data.teamId, {
+				actorUserId: user.id,
+			});
 
 			message = "Team drop out undone";
 			break;
diff --git a/app/features/tournament/actions/to.$id.join.server.ts b/app/features/tournament/actions/to.$id.join.server.ts
index e3f936462..be09a246a 100644
--- a/app/features/tournament/actions/to.$id.join.server.ts
+++ b/app/features/tournament/actions/to.$id.join.server.ts
@@ -90,6 +90,7 @@ export const action: ActionFunction = async ({ request, params }) => {
 	await TournamentLFGRepository.leaveLfg({ userId: user.id, tournamentId });
 	await TournamentTeamRepository.join({
 		userId: user.id,
+		actorUserId: user.id,
 		newTeamId: teamToJoin.id,
 		previousTeamId: previousTeam?.id,
 		// making sure they aren't unfilling one checking in condition i.e. having full roster
diff --git a/app/features/tournament/actions/to.$id.register.server.ts b/app/features/tournament/actions/to.$id.register.server.ts
index 527159089..878042dc6 100644
--- a/app/features/tournament/actions/to.$id.register.server.ts
+++ b/app/features/tournament/actions/to.$id.register.server.ts
@@ -129,6 +129,7 @@ export const action: ActionFunction = async ({ request, params }) => {
 						teamId: data.teamId ?? null,
 					},
 					userId: user.id,
+					actorUserId: user.id,
 					tournamentId,
 					avatarFileName,
 				});
@@ -165,6 +166,7 @@ export const action: ActionFunction = async ({ request, params }) => {
 			await TournamentTeamRepository.leave({
 				teamId: ownTeam.id,
 				userId: data.userId,
+				actorUserId: user.id,
 			});
 
 			ShowcaseTournaments.removeFromCached({
@@ -191,6 +193,7 @@ export const action: ActionFunction = async ({ request, params }) => {
 			await TournamentTeamRepository.leave({
 				teamId: teamMemberOf.id,
 				userId: user.id,
+				actorUserId: user.id,
 			});
 
 			ShowcaseTournaments.removeFromCached({
@@ -244,7 +247,9 @@ export const action: ActionFunction = async ({ request, params }) => {
 				`Can't check-in - ${tournament.checkInConditionsFulfilledByTeamId(teamMemberOf.id).reason}`,
 			);
 
-			await TournamentTeamRepository.checkIn(teamMemberOf.id);
+			await TournamentTeamRepository.checkIn(teamMemberOf.id, {
+				actorUserId: user.id,
+			});
 			logger.info(
 				`Checking in (success): tournament team id: ${teamMemberOf.id} - user id: ${user.id} - tournament id: ${tournamentId}`,
 			);
@@ -286,6 +291,7 @@ export const action: ActionFunction = async ({ request, params }) => {
 			});
 			await TournamentTeamRepository.join({
 				userId: data.userId,
+				actorUserId: user.id,
 				newTeamId: ownTeam.id,
 			});
 
@@ -330,7 +336,9 @@ export const action: ActionFunction = async ({ request, params }) => {
 				"Unregistering from leagues is not possible after registration has closed",
 			);
 
-			await TournamentTeamRepository.del(ownTeam.id);
+			await TournamentTeamRepository.del(ownTeam.id, {
+				actorUserId: user.id,
+			});
 
 			for (const member of ownTeam.members) {
 				ShowcaseTournaments.removeFromCached({
diff --git a/app/features/tournament/components/TournamentAdminAuditLog.module.css b/app/features/tournament/components/TournamentAdminAuditLog.module.css
new file mode 100644
index 000000000..eb170a1e0
--- /dev/null
+++ b/app/features/tournament/components/TournamentAdminAuditLog.module.css
@@ -0,0 +1,6 @@
+.userCell {
+	display: inline-flex;
+	align-items: center;
+	gap: var(--s-1-5);
+	white-space: nowrap;
+}
diff --git a/app/features/tournament/components/TournamentAdminAuditLog.tsx b/app/features/tournament/components/TournamentAdminAuditLog.tsx
new file mode 100644
index 000000000..c632f4d79
--- /dev/null
+++ b/app/features/tournament/components/TournamentAdminAuditLog.tsx
@@ -0,0 +1,211 @@
+import { useTranslation } from "react-i18next";
+import { Link, useLoaderData, useSearchParams } from "react-router";
+import { Avatar } from "~/components/Avatar";
+import { Label } from "~/components/Label";
+import { LocaleTime } from "~/components/LocaleTime";
+import { Pagination } from "~/components/Pagination";
+import { Table } from "~/components/Table";
+import { TOURNAMENT_AUDIT_LOG_TYPES } from "~/db/tables";
+import type { CommonUser } from "~/utils/kysely.server";
+import { tournamentTeamPage, userPage } from "~/utils/urls";
+import type { TournamentAdminPageLoader } from "../loaders/to.$id.admin.server";
+import { useTournament } from "../routes/to.$id";
+import styles from "./TournamentAdminAuditLog.module.css";
+
+const WHEN_FORMAT_OPTIONS = {
+	day: "numeric",
+	month: "numeric",
+	year: "numeric",
+	hour: "numeric",
+	minute: "numeric",
+} as const;
+
+// xxx: data not loaded before full page refresh
+
+export function TournamentAdminAuditLog() {
+	const { t } = useTranslation(["tournament"]);
+	const data = useLoaderData<TournamentAdminPageLoader>();
+	const [, setSearchParams] = useSearchParams();
+
+	const auditLog = data?.auditLog;
+	if (!auditLog) return null;
+
+	const setPage = (page: number) => {
+		setSearchParams((params) => {
+			params.set("page", String(page));
+			return params;
+		});
+	};
+
+	return (
+		<div className="stack md">
+			<AuditLogFilters teams={auditLog.teams} />
+			{auditLog.events.length === 0 ? (
+				<div className="text-lighter text-sm">
+					{t("tournament:admin.audit.empty")}
+				</div>
+			) : (
+				<>
+					<Table>
+						<thead>
+							<tr>
+								<th>{t("tournament:admin.audit.column.when")}</th>
+								<th>{t("tournament:admin.audit.column.event")}</th>
+								<th>{t("tournament:admin.audit.column.team")}</th>
+								<th>{t("tournament:admin.audit.column.actor")}</th>
+								<th>{t("tournament:admin.audit.column.subject")}</th>
+							</tr>
+						</thead>
+						<tbody>
+							{auditLog.events.map((event) => (
+								<AuditLogRow key={event.id} event={event} />
+							))}
+						</tbody>
+					</Table>
+					{auditLog.pagesCount > 1 ? (
+						<Pagination
+							currentPage={auditLog.currentPage}
+							pagesCount={auditLog.pagesCount}
+							nextPage={() => setPage(auditLog.currentPage + 1)}
+							previousPage={() => setPage(auditLog.currentPage - 1)}
+							setPage={setPage}
+						/>
+					) : null}
+				</>
+			)}
+		</div>
+	);
+}
+
+type AuditLogEvent = NonNullable<
+	NonNullable<
+		ReturnType<typeof useLoaderData<TournamentAdminPageLoader>>
+	>["auditLog"]
+>["events"][number];
+
+function AuditLogRow({ event }: { event: AuditLogEvent }) {
+	const { t } = useTranslation(["tournament"]);
+	const tournament = useTournament();
+
+	const bracketName =
+		typeof event.metadata?.bracketIdx === "number"
+			? tournament.brackets[event.metadata.bracketIdx]?.name
+			: undefined;
+
+	return (
+		<tr>
+			<td>
+				<LocaleTime
+					date={event.createdAt}
+					options={WHEN_FORMAT_OPTIONS}
+					inline
+				/>
+			</td>
+			<td>
+				{t(`tournament:admin.audit.event.${event.type}`)}
+				{bracketName ? (
+					<div className="text-lighter text-xs">{bracketName}</div>
+				) : null}
+			</td>
+			<td>
+				{event.team ? (
+					tournament.teamById(event.team.id) ? (
+						<Link
+							to={tournamentTeamPage({
+								tournamentId: tournament.ctx.id,
+								tournamentTeamId: event.team.id,
+							})}
+						>
+							{event.team.name}
+						</Link>
+					) : (
+						event.team.name
+					)
+				) : (
+					"-"
+				)}
+			</td>
+			<td>
+				<UserCell user={event.actor} />
+			</td>
+			<td>
+				<UserCell user={event.subject} />
+			</td>
+		</tr>
+	);
+}
+
+function UserCell({ user }: { user: CommonUser | null }) {
+	if (!user) return <>-</>;
+
+	return (
+		<Link to={userPage(user)} className={styles.userCell}>
+			<Avatar user={user} size="xxs" />
+			{user.username}
+		</Link>
+	);
+}
+
+function AuditLogFilters({
+	teams,
+}: {
+	teams: Array<{ id: number; name: string }>;
+}) {
+	const { t } = useTranslation(["tournament"]);
+	const [searchParams, setSearchParams] = useSearchParams();
+
+	const setFilter = (key: string, value: string) => {
+		setSearchParams((params) => {
+			if (value) {
+				params.set(key, value);
+			} else {
+				params.delete(key);
+			}
+			params.delete("page");
+			return params;
+		});
+	};
+
+	return (
+		<div className="stack horizontal sm flex-wrap">
+			<div>
+				<Label htmlFor="auditType">
+					{t("tournament:admin.audit.filter.event")}
+				</Label>
+				<select
+					id="auditType"
+					value={searchParams.get("auditType") ?? ""}
+					onChange={(e) => setFilter("auditType", e.target.value)}
+				>
+					<option value="">
+						{t("tournament:admin.audit.filter.allEvents")}
+					</option>
+					{TOURNAMENT_AUDIT_LOG_TYPES.map((type) => (
+						<option key={type} value={type}>
+							{t(`tournament:admin.audit.event.${type}`)}
+						</option>
+					))}
+				</select>
+			</div>
+			<div>
+				<Label htmlFor="auditTeam">
+					{t("tournament:admin.audit.filter.team")}
+				</Label>
+				<select
+					id="auditTeam"
+					value={searchParams.get("auditTeam") ?? ""}
+					onChange={(e) => setFilter("auditTeam", e.target.value)}
+				>
+					<option value="">
+						{t("tournament:admin.audit.filter.allTeams")}
+					</option>
+					{teams.map((team) => (
+						<option key={team.id} value={team.id}>
+							{team.name}
+						</option>
+					))}
+				</select>
+			</div>
+		</div>
+	);
+}
diff --git a/app/features/tournament/loaders/to.$id.admin.server.ts b/app/features/tournament/loaders/to.$id.admin.server.ts
new file mode 100644
index 000000000..f85afd7d6
--- /dev/null
+++ b/app/features/tournament/loaders/to.$id.admin.server.ts
@@ -0,0 +1,70 @@
+import type { LoaderFunctionArgs } from "react-router";
+import { z } from "zod";
+import { TOURNAMENT_AUDIT_LOG_TYPES } from "~/db/tables";
+import { requireUser } from "~/features/auth/core/user.server";
+import * as TournamentAuditLogRepository from "~/features/tournament/TournamentAuditLogRepository.server";
+import { AUDIT_LOG_PAGE_SIZE } from "~/features/tournament/TournamentAuditLogRepository.server";
+import { tournamentFromDBCached } from "~/features/tournament-bracket/core/Tournament.server";
+import {
+	parseParams,
+	parseSearchParams,
+	redirectIfPageOutOfBounds,
+} from "~/utils/remix.server";
+import { idObject } from "~/utils/zod";
+
+// xxx: extract to different file
+const auditSearchParamsSchema = z.object({
+	tab: z.string().optional().catch(undefined),
+	page: z.coerce.number().int().min(1).catch(1),
+	auditType: z.enum(TOURNAMENT_AUDIT_LOG_TYPES).optional().catch(undefined),
+	auditTeam: z.coerce.number().int().optional().catch(undefined),
+});
+
+export const loader = async ({ request, params }: LoaderFunctionArgs) => {
+	const user = requireUser();
+
+	const { id: tournamentId } = parseParams({ params, schema: idObject });
+
+	const tournament = await tournamentFromDBCached({ tournamentId, user });
+	if (!tournament.isOrganizer(user)) return null;
+
+	const { tab, page, auditType, auditTeam } = parseSearchParams({
+		request,
+		schema: auditSearchParamsSchema,
+	});
+
+	// xxx: probably just make proper different routes?
+	// the audit log is paginated server-side, so only fetch it for its own tab
+	if (tab !== "audit") return { auditLog: null };
+
+	const [events, totalCount, teams] = await Promise.all([
+		TournamentAuditLogRepository.findByTournamentId({
+			tournamentId,
+			type: auditType,
+			tournamentTeamId: auditTeam,
+			limit: AUDIT_LOG_PAGE_SIZE,
+			offset: (page - 1) * AUDIT_LOG_PAGE_SIZE,
+		}),
+		TournamentAuditLogRepository.countByTournamentId({
+			tournamentId,
+			type: auditType,
+			tournamentTeamId: auditTeam,
+		}),
+		TournamentAuditLogRepository.findTeamsByTournamentId(tournamentId),
+	]);
+
+	const pagesCount = Math.max(1, Math.ceil(totalCount / AUDIT_LOG_PAGE_SIZE));
+
+	redirectIfPageOutOfBounds({ request, page, pagesCount });
+
+	return {
+		auditLog: {
+			events,
+			teams,
+			currentPage: page,
+			pagesCount,
+		},
+	};
+};
+
+export type TournamentAdminPageLoader = typeof loader;
diff --git a/app/features/tournament/routes/to.$id.admin.tsx b/app/features/tournament/routes/to.$id.admin.tsx
index b3b24dacc..31da75e83 100644
--- a/app/features/tournament/routes/to.$id.admin.tsx
+++ b/app/features/tournament/routes/to.$id.admin.tsx
@@ -1,5 +1,13 @@
 import clsx from "clsx";
-import { ListOrdered, Trash, Trophy, Tv, UserCog, Users } from "lucide-react";
+import {
+	History,
+	ListOrdered,
+	Trash,
+	Trophy,
+	Tv,
+	UserCog,
+	Users,
+} from "lucide-react";
 import * as React from "react";
 import { useTranslation } from "react-i18next";
 import { useFetcher } from "react-router";
@@ -37,13 +45,15 @@ import {
 	tournamentPage,
 } from "~/utils/urls";
 import { BracketProgressionSelector } from "../../calendar/components/BracketProgressionSelector";
+import { TournamentAdminAuditLog } from "../components/TournamentAdminAuditLog";
 import { TournamentSeeds } from "../components/TournamentSeeds";
 import { useTournament } from "./to.$id";
 import adminStyles from "./to.$id.admin.module.css";
 
 export { action } from "../actions/to.$id.admin.server";
+export { loader } from "../loaders/to.$id.admin.server";
 
-type AdminTab = "teams" | "seeds" | "staff" | "stream" | "brackets";
+type AdminTab = "teams" | "seeds" | "staff" | "stream" | "brackets" | "audit";
 
 export default function TournamentAdminPage() {
 	const { t } = useTranslation(["tournament", "calendar"]);
@@ -75,6 +85,7 @@ export default function TournamentAdminPage() {
 		switch (tab) {
 			case "teams":
 			case "stream":
+			case "audit":
 				return true;
 			case "seeds":
 				return showSeedsTab;
@@ -160,6 +171,9 @@ export default function TournamentAdminPage() {
 							{t("tournament:admin.tab.brackets")}
 						</SendouTab>
 					) : null}
+					<SendouTab id="audit" icon={<History />}>
+						{t("tournament:admin.tab.audit")}
+					</SendouTab>
 				</SendouTabList>
 				<SendouTabPanel id="teams" className="stack lg">
 					<TeamActions />
@@ -212,6 +226,9 @@ export default function TournamentAdminPage() {
 						) : null}
 					</SendouTabPanel>
 				) : null}
+				<SendouTabPanel id="audit">
+					<TournamentAdminAuditLog />
+				</SendouTabPanel>
 			</SendouTabs>
 		</div>
 	);
diff --git a/app/features/tournament/tournament-test-utils.ts b/app/features/tournament/tournament-test-utils.ts
index 8a903b025..b18353b7d 100644
--- a/app/features/tournament/tournament-test-utils.ts
+++ b/app/features/tournament/tournament-test-utils.ts
@@ -62,6 +62,7 @@ export async function dbInsertTournamentTeam({
 			teamId: null,
 		},
 		userId: ownerId,
+		actorUserId: ownerId,
 		tournamentId,
 	});
 
@@ -70,11 +71,14 @@ export async function dbInsertTournamentTeam({
 
 		await TournamentTeamRepository.join({
 			userId: memberId,
+			actorUserId: memberId,
 			newTeamId: tournamentTeam.id,
 		});
 	}
 
-	await TournamentTeamRepository.checkIn(tournamentTeam.id);
+	await TournamentTeamRepository.checkIn(tournamentTeam.id, {
+		actorUserId: ownerId,
+	});
 }
 
 /**
diff --git a/db-test.sqlite3 b/db-test.sqlite3
index 69e1be911..938207de3 100644
Binary files a/db-test.sqlite3 and b/db-test.sqlite3 differ
diff --git a/e2e/seeds/db-seed-AB_RR.sqlite3 b/e2e/seeds/db-seed-AB_RR.sqlite3
index 91ed39710..3f7b0ba66 100644
Binary files a/e2e/seeds/db-seed-AB_RR.sqlite3 and b/e2e/seeds/db-seed-AB_RR.sqlite3 differ
diff --git a/e2e/seeds/db-seed-DEFAULT.sqlite3 b/e2e/seeds/db-seed-DEFAULT.sqlite3
index 394c2e555..eb0e46896 100644
Binary files a/e2e/seeds/db-seed-DEFAULT.sqlite3 and b/e2e/seeds/db-seed-DEFAULT.sqlite3 differ
diff --git a/e2e/seeds/db-seed-FINALIZED_BRACKET.sqlite3 b/e2e/seeds/db-seed-FINALIZED_BRACKET.sqlite3
index a38d6d8bc..8cad1139e 100644
Binary files a/e2e/seeds/db-seed-FINALIZED_BRACKET.sqlite3 and b/e2e/seeds/db-seed-FINALIZED_BRACKET.sqlite3 differ
diff --git a/e2e/seeds/db-seed-IN_SQ_MATCH.sqlite3 b/e2e/seeds/db-seed-IN_SQ_MATCH.sqlite3
index 2bc0b7179..9e5b33772 100644
Binary files a/e2e/seeds/db-seed-IN_SQ_MATCH.sqlite3 and b/e2e/seeds/db-seed-IN_SQ_MATCH.sqlite3 differ
diff --git a/e2e/seeds/db-seed-NO_SCRIMS.sqlite3 b/e2e/seeds/db-seed-NO_SCRIMS.sqlite3
index 24f14ea88..80cd16665 100644
Binary files a/e2e/seeds/db-seed-NO_SCRIMS.sqlite3 and b/e2e/seeds/db-seed-NO_SCRIMS.sqlite3 differ
diff --git a/e2e/seeds/db-seed-NO_SQ_GROUPS.sqlite3 b/e2e/seeds/db-seed-NO_SQ_GROUPS.sqlite3
index e598df12b..1ebbf7dbf 100644
Binary files a/e2e/seeds/db-seed-NO_SQ_GROUPS.sqlite3 and b/e2e/seeds/db-seed-NO_SQ_GROUPS.sqlite3 differ
diff --git a/e2e/seeds/db-seed-NO_TOURNAMENT_TEAMS.sqlite3 b/e2e/seeds/db-seed-NO_TOURNAMENT_TEAMS.sqlite3
index 8b32b634d..6d3c2c0d2 100644
Binary files a/e2e/seeds/db-seed-NO_TOURNAMENT_TEAMS.sqlite3 and b/e2e/seeds/db-seed-NO_TOURNAMENT_TEAMS.sqlite3 differ
diff --git a/e2e/seeds/db-seed-NZAP_IN_TEAM.sqlite3 b/e2e/seeds/db-seed-NZAP_IN_TEAM.sqlite3
index fd9c8331d..c45668c10 100644
Binary files a/e2e/seeds/db-seed-NZAP_IN_TEAM.sqlite3 and b/e2e/seeds/db-seed-NZAP_IN_TEAM.sqlite3 differ
diff --git a/e2e/seeds/db-seed-REG_OPEN.sqlite3 b/e2e/seeds/db-seed-REG_OPEN.sqlite3
index d164f07a6..ae4012dcd 100644
Binary files a/e2e/seeds/db-seed-REG_OPEN.sqlite3 and b/e2e/seeds/db-seed-REG_OPEN.sqlite3 differ
diff --git a/e2e/seeds/db-seed-SMALL_SOS.sqlite3 b/e2e/seeds/db-seed-SMALL_SOS.sqlite3
index 7cfc15e74..726bc703f 100644
Binary files a/e2e/seeds/db-seed-SMALL_SOS.sqlite3 and b/e2e/seeds/db-seed-SMALL_SOS.sqlite3 differ
diff --git a/e2e/seeds/db-seed-TEAM_MAP_PREFS.sqlite3 b/e2e/seeds/db-seed-TEAM_MAP_PREFS.sqlite3
index e598c3b1d..7df5aa073 100644
Binary files a/e2e/seeds/db-seed-TEAM_MAP_PREFS.sqlite3 and b/e2e/seeds/db-seed-TEAM_MAP_PREFS.sqlite3 differ
diff --git a/locales/da/tournament.json b/locales/da/tournament.json
index c68e942a8..1fefed6f8 100644
--- a/locales/da/tournament.json
+++ b/locales/da/tournament.json
@@ -80,6 +80,25 @@
 	"admin.tab.staff": "",
 	"admin.tab.stream": "",
 	"admin.tab.brackets": "",
+	"admin.tab.audit": "",
+	"admin.audit.empty": "",
+	"admin.audit.filter.event": "",
+	"admin.audit.filter.team": "",
+	"admin.audit.filter.allEvents": "",
+	"admin.audit.filter.allTeams": "",
+	"admin.audit.column.when": "",
+	"admin.audit.column.event": "",
+	"admin.audit.column.team": "",
+	"admin.audit.column.actor": "",
+	"admin.audit.column.subject": "",
+	"admin.audit.event.MEMBER_ADDED": "",
+	"admin.audit.event.MEMBER_REMOVED": "",
+	"admin.audit.event.TEAM_REGISTERED": "",
+	"admin.audit.event.TEAM_UNREGISTERED": "",
+	"admin.audit.event.TEAM_CHECKED_IN": "",
+	"admin.audit.event.TEAM_CHECKED_OUT": "",
+	"admin.audit.event.TEAM_DROPPED_OUT": "",
+	"admin.audit.event.TEAM_DROP_OUT_UNDONE": "",
 	"admin.actions.CHANGE_TEAM_OWNER": "Ændr holdkaptajn",
 	"admin.actions.CHANGE_TEAM_NAME": "Ændr holdnavn",
 	"admin.actions.CHECK_IN": "Tjek ind",
diff --git a/locales/de/tournament.json b/locales/de/tournament.json
index 9c52de71c..4c6fa778a 100644
--- a/locales/de/tournament.json
+++ b/locales/de/tournament.json
@@ -80,6 +80,25 @@
 	"admin.tab.staff": "",
 	"admin.tab.stream": "",
 	"admin.tab.brackets": "",
+	"admin.tab.audit": "",
+	"admin.audit.empty": "",
+	"admin.audit.filter.event": "",
+	"admin.audit.filter.team": "",
+	"admin.audit.filter.allEvents": "",
+	"admin.audit.filter.allTeams": "",
+	"admin.audit.column.when": "",
+	"admin.audit.column.event": "",
+	"admin.audit.column.team": "",
+	"admin.audit.column.actor": "",
+	"admin.audit.column.subject": "",
+	"admin.audit.event.MEMBER_ADDED": "",
+	"admin.audit.event.MEMBER_REMOVED": "",
+	"admin.audit.event.TEAM_REGISTERED": "",
+	"admin.audit.event.TEAM_UNREGISTERED": "",
+	"admin.audit.event.TEAM_CHECKED_IN": "",
+	"admin.audit.event.TEAM_CHECKED_OUT": "",
+	"admin.audit.event.TEAM_DROPPED_OUT": "",
+	"admin.audit.event.TEAM_DROP_OUT_UNDONE": "",
 	"admin.actions.CHANGE_TEAM_OWNER": "Kapitän ändern",
 	"admin.actions.CHANGE_TEAM_NAME": "Teamnamen ändern",
 	"admin.actions.CHECK_IN": "Einchecken",
diff --git a/locales/en/tournament.json b/locales/en/tournament.json
index f524bf4f6..c6545320e 100644
--- a/locales/en/tournament.json
+++ b/locales/en/tournament.json
@@ -80,6 +80,25 @@
 	"admin.tab.staff": "Staff",
 	"admin.tab.stream": "Stream",
 	"admin.tab.brackets": "Brackets",
+	"admin.tab.audit": "Audit log",
+	"admin.audit.empty": "No events yet",
+	"admin.audit.filter.event": "Event",
+	"admin.audit.filter.team": "Team",
+	"admin.audit.filter.allEvents": "All events",
+	"admin.audit.filter.allTeams": "All teams",
+	"admin.audit.column.when": "When",
+	"admin.audit.column.event": "Event",
+	"admin.audit.column.team": "Team",
+	"admin.audit.column.actor": "By",
+	"admin.audit.column.subject": "Affected player",
+	"admin.audit.event.MEMBER_ADDED": "Player joined team",
+	"admin.audit.event.MEMBER_REMOVED": "Player left team",
+	"admin.audit.event.TEAM_REGISTERED": "Team registered",
+	"admin.audit.event.TEAM_UNREGISTERED": "Team unregistered",
+	"admin.audit.event.TEAM_CHECKED_IN": "Team checked in",
+	"admin.audit.event.TEAM_CHECKED_OUT": "Team checked out",
+	"admin.audit.event.TEAM_DROPPED_OUT": "Team dropped out",
+	"admin.audit.event.TEAM_DROP_OUT_UNDONE": "Team drop out undone",
 	"admin.actions.CHANGE_TEAM_OWNER": "Change captain",
 	"admin.actions.CHANGE_TEAM_NAME": "Change team name",
 	"admin.actions.CHECK_IN": "Check in",
diff --git a/locales/es-ES/tournament.json b/locales/es-ES/tournament.json
index 53b4199e3..d91cb35f1 100644
--- a/locales/es-ES/tournament.json
+++ b/locales/es-ES/tournament.json
@@ -81,6 +81,25 @@
 	"admin.tab.staff": "",
 	"admin.tab.stream": "",
 	"admin.tab.brackets": "",
+	"admin.tab.audit": "",
+	"admin.audit.empty": "",
+	"admin.audit.filter.event": "",
+	"admin.audit.filter.team": "",
+	"admin.audit.filter.allEvents": "",
+	"admin.audit.filter.allTeams": "",
+	"admin.audit.column.when": "",
+	"admin.audit.column.event": "",
+	"admin.audit.column.team": "",
+	"admin.audit.column.actor": "",
+	"admin.audit.column.subject": "",
+	"admin.audit.event.MEMBER_ADDED": "",
+	"admin.audit.event.MEMBER_REMOVED": "",
+	"admin.audit.event.TEAM_REGISTERED": "",
+	"admin.audit.event.TEAM_UNREGISTERED": "",
+	"admin.audit.event.TEAM_CHECKED_IN": "",
+	"admin.audit.event.TEAM_CHECKED_OUT": "",
+	"admin.audit.event.TEAM_DROPPED_OUT": "",
+	"admin.audit.event.TEAM_DROP_OUT_UNDONE": "",
 	"admin.actions.CHANGE_TEAM_OWNER": "Cambiar capitán",
 	"admin.actions.CHANGE_TEAM_NAME": "Cambiar nombre de equipo",
 	"admin.actions.CHECK_IN": "Check in",
diff --git a/locales/es-US/tournament.json b/locales/es-US/tournament.json
index 35e3f14d8..4803faa3f 100644
--- a/locales/es-US/tournament.json
+++ b/locales/es-US/tournament.json
@@ -81,6 +81,25 @@
 	"admin.tab.staff": "",
 	"admin.tab.stream": "",
 	"admin.tab.brackets": "",
+	"admin.tab.audit": "",
+	"admin.audit.empty": "",
+	"admin.audit.filter.event": "",
+	"admin.audit.filter.team": "",
+	"admin.audit.filter.allEvents": "",
+	"admin.audit.filter.allTeams": "",
+	"admin.audit.column.when": "",
+	"admin.audit.column.event": "",
+	"admin.audit.column.team": "",
+	"admin.audit.column.actor": "",
+	"admin.audit.column.subject": "",
+	"admin.audit.event.MEMBER_ADDED": "",
+	"admin.audit.event.MEMBER_REMOVED": "",
+	"admin.audit.event.TEAM_REGISTERED": "",
+	"admin.audit.event.TEAM_UNREGISTERED": "",
+	"admin.audit.event.TEAM_CHECKED_IN": "",
+	"admin.audit.event.TEAM_CHECKED_OUT": "",
+	"admin.audit.event.TEAM_DROPPED_OUT": "",
+	"admin.audit.event.TEAM_DROP_OUT_UNDONE": "",
 	"admin.actions.CHANGE_TEAM_OWNER": "Cambiar capitán",
 	"admin.actions.CHANGE_TEAM_NAME": "Cambiar nombre de equipo",
 	"admin.actions.CHECK_IN": "Check in",
diff --git a/locales/fr-CA/tournament.json b/locales/fr-CA/tournament.json
index 257c759e6..5da7c1439 100644
--- a/locales/fr-CA/tournament.json
+++ b/locales/fr-CA/tournament.json
@@ -81,6 +81,25 @@
 	"admin.tab.staff": "",
 	"admin.tab.stream": "",
 	"admin.tab.brackets": "",
+	"admin.tab.audit": "",
+	"admin.audit.empty": "",
+	"admin.audit.filter.event": "",
+	"admin.audit.filter.team": "",
+	"admin.audit.filter.allEvents": "",
+	"admin.audit.filter.allTeams": "",
+	"admin.audit.column.when": "",
+	"admin.audit.column.event": "",
+	"admin.audit.column.team": "",
+	"admin.audit.column.actor": "",
+	"admin.audit.column.subject": "",
+	"admin.audit.event.MEMBER_ADDED": "",
+	"admin.audit.event.MEMBER_REMOVED": "",
+	"admin.audit.event.TEAM_REGISTERED": "",
+	"admin.audit.event.TEAM_UNREGISTERED": "",
+	"admin.audit.event.TEAM_CHECKED_IN": "",
+	"admin.audit.event.TEAM_CHECKED_OUT": "",
+	"admin.audit.event.TEAM_DROPPED_OUT": "",
+	"admin.audit.event.TEAM_DROP_OUT_UNDONE": "",
 	"admin.actions.CHANGE_TEAM_OWNER": "Changer le capitaine",
 	"admin.actions.CHANGE_TEAM_NAME": "",
 	"admin.actions.CHECK_IN": "S'enregister",
diff --git a/locales/fr-EU/tournament.json b/locales/fr-EU/tournament.json
index 0f6064dfb..cddb3b5a2 100644
--- a/locales/fr-EU/tournament.json
+++ b/locales/fr-EU/tournament.json
@@ -81,6 +81,25 @@
 	"admin.tab.staff": "",
 	"admin.tab.stream": "",
 	"admin.tab.brackets": "",
+	"admin.tab.audit": "",
+	"admin.audit.empty": "",
+	"admin.audit.filter.event": "",
+	"admin.audit.filter.team": "",
+	"admin.audit.filter.allEvents": "",
+	"admin.audit.filter.allTeams": "",
+	"admin.audit.column.when": "",
+	"admin.audit.column.event": "",
+	"admin.audit.column.team": "",
+	"admin.audit.column.actor": "",
+	"admin.audit.column.subject": "",
+	"admin.audit.event.MEMBER_ADDED": "",
+	"admin.audit.event.MEMBER_REMOVED": "",
+	"admin.audit.event.TEAM_REGISTERED": "",
+	"admin.audit.event.TEAM_UNREGISTERED": "",
+	"admin.audit.event.TEAM_CHECKED_IN": "",
+	"admin.audit.event.TEAM_CHECKED_OUT": "",
+	"admin.audit.event.TEAM_DROPPED_OUT": "",
+	"admin.audit.event.TEAM_DROP_OUT_UNDONE": "",
 	"admin.actions.CHANGE_TEAM_OWNER": "Changer le capitaine",
 	"admin.actions.CHANGE_TEAM_NAME": "Changer le nom de l'équipe ",
 	"admin.actions.CHECK_IN": "S'enregister",
diff --git a/locales/he/tournament.json b/locales/he/tournament.json
index d56648e3a..3b00e324f 100644
--- a/locales/he/tournament.json
+++ b/locales/he/tournament.json
@@ -81,6 +81,25 @@
 	"admin.tab.staff": "",
 	"admin.tab.stream": "",
 	"admin.tab.brackets": "",
+	"admin.tab.audit": "",
+	"admin.audit.empty": "",
+	"admin.audit.filter.event": "",
+	"admin.audit.filter.team": "",
+	"admin.audit.filter.allEvents": "",
+	"admin.audit.filter.allTeams": "",
+	"admin.audit.column.when": "",
+	"admin.audit.column.event": "",
+	"admin.audit.column.team": "",
+	"admin.audit.column.actor": "",
+	"admin.audit.column.subject": "",
+	"admin.audit.event.MEMBER_ADDED": "",
+	"admin.audit.event.MEMBER_REMOVED": "",
+	"admin.audit.event.TEAM_REGISTERED": "",
+	"admin.audit.event.TEAM_UNREGISTERED": "",
+	"admin.audit.event.TEAM_CHECKED_IN": "",
+	"admin.audit.event.TEAM_CHECKED_OUT": "",
+	"admin.audit.event.TEAM_DROPPED_OUT": "",
+	"admin.audit.event.TEAM_DROP_OUT_UNDONE": "",
 	"admin.actions.CHANGE_TEAM_OWNER": "שינוי קפטן",
 	"admin.actions.CHANGE_TEAM_NAME": "",
 	"admin.actions.CHECK_IN": "קבלה",
diff --git a/locales/it/tournament.json b/locales/it/tournament.json
index cf0ccecf2..4bfa34755 100644
--- a/locales/it/tournament.json
+++ b/locales/it/tournament.json
@@ -81,6 +81,25 @@
 	"admin.tab.staff": "",
 	"admin.tab.stream": "",
 	"admin.tab.brackets": "",
+	"admin.tab.audit": "",
+	"admin.audit.empty": "",
+	"admin.audit.filter.event": "",
+	"admin.audit.filter.team": "",
+	"admin.audit.filter.allEvents": "",
+	"admin.audit.filter.allTeams": "",
+	"admin.audit.column.when": "",
+	"admin.audit.column.event": "",
+	"admin.audit.column.team": "",
+	"admin.audit.column.actor": "",
+	"admin.audit.column.subject": "",
+	"admin.audit.event.MEMBER_ADDED": "",
+	"admin.audit.event.MEMBER_REMOVED": "",
+	"admin.audit.event.TEAM_REGISTERED": "",
+	"admin.audit.event.TEAM_UNREGISTERED": "",
+	"admin.audit.event.TEAM_CHECKED_IN": "",
+	"admin.audit.event.TEAM_CHECKED_OUT": "",
+	"admin.audit.event.TEAM_DROPPED_OUT": "",
+	"admin.audit.event.TEAM_DROP_OUT_UNDONE": "",
 	"admin.actions.CHANGE_TEAM_OWNER": "Cambia capitano",
 	"admin.actions.CHANGE_TEAM_NAME": "Cambia nome team",
 	"admin.actions.CHECK_IN": "Check-in",
diff --git a/locales/ja/tournament.json b/locales/ja/tournament.json
index 428712df1..6df979394 100644
--- a/locales/ja/tournament.json
+++ b/locales/ja/tournament.json
@@ -78,6 +78,25 @@
 	"admin.tab.staff": "",
 	"admin.tab.stream": "",
 	"admin.tab.brackets": "",
+	"admin.tab.audit": "",
+	"admin.audit.empty": "",
+	"admin.audit.filter.event": "",
+	"admin.audit.filter.team": "",
+	"admin.audit.filter.allEvents": "",
+	"admin.audit.filter.allTeams": "",
+	"admin.audit.column.when": "",
+	"admin.audit.column.event": "",
+	"admin.audit.column.team": "",
+	"admin.audit.column.actor": "",
+	"admin.audit.column.subject": "",
+	"admin.audit.event.MEMBER_ADDED": "",
+	"admin.audit.event.MEMBER_REMOVED": "",
+	"admin.audit.event.TEAM_REGISTERED": "",
+	"admin.audit.event.TEAM_UNREGISTERED": "",
+	"admin.audit.event.TEAM_CHECKED_IN": "",
+	"admin.audit.event.TEAM_CHECKED_OUT": "",
+	"admin.audit.event.TEAM_DROPPED_OUT": "",
+	"admin.audit.event.TEAM_DROP_OUT_UNDONE": "",
 	"admin.actions.CHANGE_TEAM_OWNER": "キャプテンを変更",
 	"admin.actions.CHANGE_TEAM_NAME": "チーム名変更",
 	"admin.actions.CHECK_IN": "チェックイン",
diff --git a/locales/ko/tournament.json b/locales/ko/tournament.json
index c75df3382..c1dfbee95 100644
--- a/locales/ko/tournament.json
+++ b/locales/ko/tournament.json
@@ -78,6 +78,25 @@
 	"admin.tab.staff": "",
 	"admin.tab.stream": "",
 	"admin.tab.brackets": "",
+	"admin.tab.audit": "",
+	"admin.audit.empty": "",
+	"admin.audit.filter.event": "",
+	"admin.audit.filter.team": "",
+	"admin.audit.filter.allEvents": "",
+	"admin.audit.filter.allTeams": "",
+	"admin.audit.column.when": "",
+	"admin.audit.column.event": "",
+	"admin.audit.column.team": "",
+	"admin.audit.column.actor": "",
+	"admin.audit.column.subject": "",
+	"admin.audit.event.MEMBER_ADDED": "",
+	"admin.audit.event.MEMBER_REMOVED": "",
+	"admin.audit.event.TEAM_REGISTERED": "",
+	"admin.audit.event.TEAM_UNREGISTERED": "",
+	"admin.audit.event.TEAM_CHECKED_IN": "",
+	"admin.audit.event.TEAM_CHECKED_OUT": "",
+	"admin.audit.event.TEAM_DROPPED_OUT": "",
+	"admin.audit.event.TEAM_DROP_OUT_UNDONE": "",
 	"admin.actions.CHANGE_TEAM_OWNER": "",
 	"admin.actions.CHANGE_TEAM_NAME": "",
 	"admin.actions.CHECK_IN": "",
diff --git a/locales/nl/tournament.json b/locales/nl/tournament.json
index 00370fae1..5fdf9fe5f 100644
--- a/locales/nl/tournament.json
+++ b/locales/nl/tournament.json
@@ -80,6 +80,25 @@
 	"admin.tab.staff": "",
 	"admin.tab.stream": "",
 	"admin.tab.brackets": "",
+	"admin.tab.audit": "",
+	"admin.audit.empty": "",
+	"admin.audit.filter.event": "",
+	"admin.audit.filter.team": "",
+	"admin.audit.filter.allEvents": "",
+	"admin.audit.filter.allTeams": "",
+	"admin.audit.column.when": "",
+	"admin.audit.column.event": "",
+	"admin.audit.column.team": "",
+	"admin.audit.column.actor": "",
+	"admin.audit.column.subject": "",
+	"admin.audit.event.MEMBER_ADDED": "",
+	"admin.audit.event.MEMBER_REMOVED": "",
+	"admin.audit.event.TEAM_REGISTERED": "",
+	"admin.audit.event.TEAM_UNREGISTERED": "",
+	"admin.audit.event.TEAM_CHECKED_IN": "",
+	"admin.audit.event.TEAM_CHECKED_OUT": "",
+	"admin.audit.event.TEAM_DROPPED_OUT": "",
+	"admin.audit.event.TEAM_DROP_OUT_UNDONE": "",
 	"admin.actions.CHANGE_TEAM_OWNER": "",
 	"admin.actions.CHANGE_TEAM_NAME": "",
 	"admin.actions.CHECK_IN": "",
diff --git a/locales/pl/tournament.json b/locales/pl/tournament.json
index 707b5fb52..6c63755d4 100644
--- a/locales/pl/tournament.json
+++ b/locales/pl/tournament.json
@@ -82,6 +82,25 @@
 	"admin.tab.staff": "",
 	"admin.tab.stream": "",
 	"admin.tab.brackets": "",
+	"admin.tab.audit": "",
+	"admin.audit.empty": "",
+	"admin.audit.filter.event": "",
+	"admin.audit.filter.team": "",
+	"admin.audit.filter.allEvents": "",
+	"admin.audit.filter.allTeams": "",
+	"admin.audit.column.when": "",
+	"admin.audit.column.event": "",
+	"admin.audit.column.team": "",
+	"admin.audit.column.actor": "",
+	"admin.audit.column.subject": "",
+	"admin.audit.event.MEMBER_ADDED": "",
+	"admin.audit.event.MEMBER_REMOVED": "",
+	"admin.audit.event.TEAM_REGISTERED": "",
+	"admin.audit.event.TEAM_UNREGISTERED": "",
+	"admin.audit.event.TEAM_CHECKED_IN": "",
+	"admin.audit.event.TEAM_CHECKED_OUT": "",
+	"admin.audit.event.TEAM_DROPPED_OUT": "",
+	"admin.audit.event.TEAM_DROP_OUT_UNDONE": "",
 	"admin.actions.CHANGE_TEAM_OWNER": "",
 	"admin.actions.CHANGE_TEAM_NAME": "",
 	"admin.actions.CHECK_IN": "",
diff --git a/locales/pt-BR/tournament.json b/locales/pt-BR/tournament.json
index 05f7f3cf7..f56f55e35 100644
--- a/locales/pt-BR/tournament.json
+++ b/locales/pt-BR/tournament.json
@@ -81,6 +81,25 @@
 	"admin.tab.staff": "",
 	"admin.tab.stream": "",
 	"admin.tab.brackets": "",
+	"admin.tab.audit": "",
+	"admin.audit.empty": "",
+	"admin.audit.filter.event": "",
+	"admin.audit.filter.team": "",
+	"admin.audit.filter.allEvents": "",
+	"admin.audit.filter.allTeams": "",
+	"admin.audit.column.when": "",
+	"admin.audit.column.event": "",
+	"admin.audit.column.team": "",
+	"admin.audit.column.actor": "",
+	"admin.audit.column.subject": "",
+	"admin.audit.event.MEMBER_ADDED": "",
+	"admin.audit.event.MEMBER_REMOVED": "",
+	"admin.audit.event.TEAM_REGISTERED": "",
+	"admin.audit.event.TEAM_UNREGISTERED": "",
+	"admin.audit.event.TEAM_CHECKED_IN": "",
+	"admin.audit.event.TEAM_CHECKED_OUT": "",
+	"admin.audit.event.TEAM_DROPPED_OUT": "",
+	"admin.audit.event.TEAM_DROP_OUT_UNDONE": "",
 	"admin.actions.CHANGE_TEAM_OWNER": "Mudar capitão",
 	"admin.actions.CHANGE_TEAM_NAME": "Mudar nome do time",
 	"admin.actions.CHECK_IN": "Check-in",
diff --git a/locales/ru/tournament.json b/locales/ru/tournament.json
index ec304d7f2..ed5a5c38f 100644
--- a/locales/ru/tournament.json
+++ b/locales/ru/tournament.json
@@ -82,6 +82,25 @@
 	"admin.tab.staff": "",
 	"admin.tab.stream": "",
 	"admin.tab.brackets": "",
+	"admin.tab.audit": "",
+	"admin.audit.empty": "",
+	"admin.audit.filter.event": "",
+	"admin.audit.filter.team": "",
+	"admin.audit.filter.allEvents": "",
+	"admin.audit.filter.allTeams": "",
+	"admin.audit.column.when": "",
+	"admin.audit.column.event": "",
+	"admin.audit.column.team": "",
+	"admin.audit.column.actor": "",
+	"admin.audit.column.subject": "",
+	"admin.audit.event.MEMBER_ADDED": "",
+	"admin.audit.event.MEMBER_REMOVED": "",
+	"admin.audit.event.TEAM_REGISTERED": "",
+	"admin.audit.event.TEAM_UNREGISTERED": "",
+	"admin.audit.event.TEAM_CHECKED_IN": "",
+	"admin.audit.event.TEAM_CHECKED_OUT": "",
+	"admin.audit.event.TEAM_DROPPED_OUT": "",
+	"admin.audit.event.TEAM_DROP_OUT_UNDONE": "",
 	"admin.actions.CHANGE_TEAM_OWNER": "Изменить капитана",
 	"admin.actions.CHANGE_TEAM_NAME": "Изменить имя команды",
 	"admin.actions.CHECK_IN": "Зарегистрировать",
diff --git a/locales/zh/tournament.json b/locales/zh/tournament.json
index 4fe48653c..92346ecd9 100644
--- a/locales/zh/tournament.json
+++ b/locales/zh/tournament.json
@@ -78,6 +78,25 @@
 	"admin.tab.staff": "",
 	"admin.tab.stream": "",
 	"admin.tab.brackets": "",
+	"admin.tab.audit": "",
+	"admin.audit.empty": "",
+	"admin.audit.filter.event": "",
+	"admin.audit.filter.team": "",
+	"admin.audit.filter.allEvents": "",
+	"admin.audit.filter.allTeams": "",
+	"admin.audit.column.when": "",
+	"admin.audit.column.event": "",
+	"admin.audit.column.team": "",
+	"admin.audit.column.actor": "",
+	"admin.audit.column.subject": "",
+	"admin.audit.event.MEMBER_ADDED": "",
+	"admin.audit.event.MEMBER_REMOVED": "",
+	"admin.audit.event.TEAM_REGISTERED": "",
+	"admin.audit.event.TEAM_UNREGISTERED": "",
+	"admin.audit.event.TEAM_CHECKED_IN": "",
+	"admin.audit.event.TEAM_CHECKED_OUT": "",
+	"admin.audit.event.TEAM_DROPPED_OUT": "",
+	"admin.audit.event.TEAM_DROP_OUT_UNDONE": "",
 	"admin.actions.CHANGE_TEAM_OWNER": "变更队长",
 	"admin.actions.CHANGE_TEAM_NAME": "变更队名",
 	"admin.actions.CHECK_IN": "登入",
diff --git a/migrations/145-tournament-audit-log.js b/migrations/145-tournament-audit-log.js
new file mode 100644
index 000000000..0d817d8c9
--- /dev/null
+++ b/migrations/145-tournament-audit-log.js
@@ -0,0 +1,52 @@
+export function up(db) {
+	db.transaction(() => {
+		db.prepare(
+			/* sql */ `
+				create table "TournamentTeamHistory" (
+					"tournamentTeamId" integer primary key,
+					"tournamentId" integer not null,
+					"name" text not null,
+					foreign key ("tournamentId") references "Tournament"("id") on delete cascade
+				) strict
+			`,
+		).run();
+
+		// xxx: no enum check, we will keep it dynamic
+		db.prepare(
+			/* sql */ `
+				create table "TournamentAuditLog" (
+					"id" integer primary key autoincrement,
+					"tournamentId" integer not null,
+					"type" text not null check (
+						"type" in (
+							'MEMBER_ADDED',
+							'MEMBER_REMOVED',
+							'TEAM_REGISTERED',
+							'TEAM_UNREGISTERED',
+							'TEAM_CHECKED_IN',
+							'TEAM_CHECKED_OUT',
+							'TEAM_DROPPED_OUT',
+							'TEAM_DROP_OUT_UNDONE'
+						)
+					),
+					"actorUserId" integer not null,
+					"subjectUserId" integer,
+					"tournamentTeamId" integer,
+					"metadata" text,
+					"createdAt" integer not null,
+					foreign key ("tournamentId") references "Tournament"("id") on delete cascade,
+					foreign key ("actorUserId") references "User"("id"),
+					foreign key ("subjectUserId") references "User"("id"),
+					foreign key ("tournamentTeamId") references "TournamentTeamHistory"("tournamentTeamId")
+				) strict
+			`,
+		).run();
+
+		// xxx: which indexes are the best?
+		db.prepare(
+			/* sql */ `create index tournament_audit_log_tournament_id_created_at_idx on "TournamentAuditLog"("tournamentId", "createdAt")`,
+		).run();
+
+		db.pragma("foreign_key_check");
+	})();
+}
diff --git a/scripts/add-leaderboard-teams-to-tournament.ts b/scripts/add-leaderboard-teams-to-tournament.ts
index 1e6bb9830..ac8a9435c 100644
--- a/scripts/add-leaderboard-teams-to-tournament.ts
+++ b/scripts/add-leaderboard-teams-to-tournament.ts
@@ -107,6 +107,7 @@ async function main() {
 				teamId: entry.team?.id ?? null,
 			},
 			userId: owner.id,
+			actorUserId: owner.id,
 			tournamentId,
 		});
 
@@ -114,6 +115,7 @@ async function main() {
 			await TournamentTeamRepository.join({
 				newTeamId: tournamentTeam.id,
 				userId: member.id,
+				actorUserId: member.id,
 			});
 		}