diff --git a/app/features/team/team-schemas.server.ts b/app/features/team/team-schemas.server.ts
index adfc92a43..55f0b7508 100644
--- a/app/features/team/team-schemas.server.ts
+++ b/app/features/team/team-schemas.server.ts
@@ -1,20 +1,20 @@
 import { z } from "zod";
 import {
 	_action,
-	actuallyNonEmptyStringOrNull,
 	customCssVarObject,
 	falsyToNull,
 	id,
+	safeStringSchema,
 } from "~/utils/zod";
 import { TEAM, TEAM_MEMBER_ROLES } from "./team-constants";
 
 export const teamParamsSchema = z.object({ customUrl: z.string() });
 
 export const createTeamSchema = z.object({
-	name: z.preprocess(
-		actuallyNonEmptyStringOrNull,
-		z.string().min(TEAM.NAME_MIN_LENGTH).max(TEAM.NAME_MAX_LENGTH),
-	),
+	name: safeStringSchema({
+		min: TEAM.NAME_MIN_LENGTH,
+		max: TEAM.NAME_MAX_LENGTH,
+	}),
 });
 
 export const teamProfilePageActionSchema = z.union([
diff --git a/app/features/tournament/tournament-schemas.server.ts b/app/features/tournament/tournament-schemas.server.ts
index a10fdbaa8..9790b9fe5 100644
--- a/app/features/tournament/tournament-schemas.server.ts
+++ b/app/features/tournament/tournament-schemas.server.ts
@@ -1,21 +1,20 @@
 import { z } from "zod";
 import {
 	_action,
-	actuallyNonEmptyStringOrNull,
 	checkboxValueToBoolean,
 	id,
 	modeShort,
 	optionalId,
 	safeJSONParse,
+	safeStringSchema,
 	stageId,
 } from "~/utils/zod";
 import { bracketIdx } from "../tournament-bracket/tournament-bracket-schemas.server";
 import { TOURNAMENT } from "./tournament-constants";
 
-export const teamName = z.preprocess(
-	actuallyNonEmptyStringOrNull,
-	z.string().max(TOURNAMENT.TEAM_NAME_MAX_LENGTH),
-);
+export const teamName = safeStringSchema({
+	max: TOURNAMENT.TEAM_NAME_MAX_LENGTH,
+});
 
 export const registerSchema = z.union([
 	z.object({
diff --git a/app/features/user-page/user-page-schemas.server.ts b/app/features/user-page/user-page-schemas.server.ts
index 31f59aed4..8bc258944 100644
--- a/app/features/user-page/user-page-schemas.server.ts
+++ b/app/features/user-page/user-page-schemas.server.ts
@@ -5,7 +5,6 @@ import "~/styles/u-edit.css";
 import { isCustomUrl } from "~/utils/urls";
 import {
 	actualNumber,
-	actuallyNonEmptyStringOrNull,
 	checkboxValueToDbBoolean,
 	customCssVarObject,
 	dbBoolean,
@@ -13,6 +12,7 @@ import {
 	id,
 	processMany,
 	safeJSONParse,
+	safeNullableStringSchema,
 	undefinedToNull,
 	weaponSplId,
 } from "~/utils/zod";
@@ -62,10 +62,7 @@ export const userEditActionSchema = z
 				.transform((val) => val?.toLowerCase())
 				.nullable(),
 		),
-		customName: z.preprocess(
-			actuallyNonEmptyStringOrNull,
-			z.string().max(USER.CUSTOM_NAME_MAX_LENGTH).nullable(),
-		),
+		customName: safeNullableStringSchema({ max: USER.CUSTOM_NAME_MAX_LENGTH }),
 		battlefy: z.preprocess(
 			falsyToNull,
 			z.string().max(USER.BATTLEFY_MAX_LENGTH).nullable(),
diff --git a/app/utils/zod.test.ts b/app/utils/zod.test.ts
index 0cd875a99..8bc407578 100644
--- a/app/utils/zod.test.ts
+++ b/app/utils/zod.test.ts
@@ -1,5 +1,5 @@
 import { describe, expect, it } from "vitest";
-import { normalizeFriendCode } from "./zod";
+import { hasZalgo, normalizeFriendCode } from "./zod";
 
 describe("normalizeFriendCode", () => {
 	it("returns well formatted friend code as is", () => {
@@ -18,3 +18,25 @@ describe("normalizeFriendCode", () => {
 		expect(normalizeFriendCode("SW-1234-56789012")).toBe("1234-5678-9012");
 	});
 });
+
+describe("hasZalgo", () => {
+	it("returns true for text containing Zalgo characters", () => {
+		expect(hasZalgo("z͎͗ͣḁ̵̑l̉̃ͦg̐̓̒o͓̔ͥ")).toBe(true);
+	});
+
+	it("returns false for text without Zalgo characters", () => {
+		expect(hasZalgo("normal text")).toBe(false);
+	});
+
+	it("returns false for an empty string", () => {
+		expect(hasZalgo("")).toBe(false);
+	});
+
+	it("returns false for text with special but non-Zalgo characters", () => {
+		expect(hasZalgo("!@#$%^&*()")).toBe(false);
+	});
+
+	it("accepts japanese characters", () => {
+		expect(hasZalgo("こんにちは")).toBe(false);
+	});
+});
diff --git a/app/utils/zod.ts b/app/utils/zod.ts
index 970651f0e..458a30246 100644
--- a/app/utils/zod.ts
+++ b/app/utils/zod.ts
@@ -123,10 +123,50 @@ export function safeJSONParse(value: unknown): unknown {
 const EMPTY_CHARACTERS = ["\u200B", "\u200C", "\u200D", "\u200E", "\u200F"];
 const EMPTY_CHARACTERS_REGEX = new RegExp(EMPTY_CHARACTERS.join("|"), "g");
 
+const zalgoRe = /%CC%/g;
+export const hasZalgo = (txt: string) => zalgoRe.test(encodeURIComponent(txt));
+
+/** Non-empty string that has the given length (max and optionally min). Prevents z͎͗ͣḁ̵̑l̉̃ͦg̐̓̒o͓̔ͥ text as well as filters out characters that have no width. */
+export const safeStringSchema = ({ min, max }: { min?: number; max: number }) =>
+	z.preprocess(
+		actuallyNonEmptyStringOrNull, // if this returns null, none of the checks below will run because it's not a string
+		z
+			.string()
+			.min(min ?? 0)
+			.max(max)
+			.refine((text) => !hasZalgo(text), {
+				message: "Includes not allowed characters.",
+			}),
+	);
+
+/** Nullable string that has the given length (max and optionally min). Prevents z͎͗ͣḁ̵̑l̉̃ͦg̐̓̒o͓̔ͥ text as well as filters out characters that have no width. */
+export const safeNullableStringSchema = ({
+	min,
+	max,
+}: { min?: number; max: number }) =>
+	z.preprocess(
+		actuallyNonEmptyStringOrNull,
+		z
+			.string()
+			.min(min ?? 0)
+			.max(max)
+			.nullable()
+			.refine(
+				(text) => {
+					if (typeof text !== "string") return true;
+
+					return !hasZalgo(text);
+				},
+				{
+					message: "Includes not allowed characters.",
+				},
+			),
+	);
+
 /**
  * Processes the input value and returns a non-empty string with invisible characters cleaned out or null.
  */
-export function actuallyNonEmptyStringOrNull(value: unknown) {
+function actuallyNonEmptyStringOrNull(value: unknown) {
 	if (typeof value !== "string") return value;
 
 	const trimmed = value.replace(EMPTY_CHARACTERS_REGEX, "").trim();