Merge branch 'canary' into 01-16-2026/fix-readme

docs/content/docs/reference/options.mdx

@@ -543,7 +543,8 @@ export const auth = betterAuth({
 			})) | false | "serial" | "uuid",
 			defaultFindManyLimit: 100,
 			experimentalJoins: false,
-		}
+		},
+		skipTrailingSlashes: true
 	},
 })
 ```
@@ -557,6 +558,7 @@ export const auth = betterAuth({
 - `defaultCookieAttributes`: Default attributes for all cookies
 - `cookiePrefix`: Prefix for cookies
 - `database`: Database configuration options
+- `skipTrailingSlashes`: Skip trailing slash validation in route matching. (default: `false`)
 - OAuth state configuration options (`storeStateStrategy`, `skipStateCookieCheck`) are now part of the `account` option
 
 ## `logger`

packages/better-auth/src/api/index.test.ts

@@ -183,3 +183,59 @@ describe("onRequest chain", () => {
 		expect(result.error?.status).toBe(403);
 	});
 });
+
+describe("skipTrailingSlashes option", () => {
+	it("should return 404 for trailing slash requests by default", async () => {
+		const { auth } = await getTestInstance({});
+
+		const response = await auth.handler(
+			new Request("http://localhost:3000/api/auth/ok/", {
+				method: "GET",
+			}),
+		);
+
+		expect(response.status).toBe(404);
+	});
+
+	it("should handle trailing slash requests when skipTrailingSlashes is enabled", async () => {
+		const { auth } = await getTestInstance({
+			advanced: {
+				skipTrailingSlashes: true,
+			},
+		});
+
+		const response = await auth.handler(
+			new Request("http://localhost:3000/api/auth/ok/", {
+				method: "GET",
+			}),
+		);
+
+		expect(response.status).toBe(200);
+		const body = await response.json();
+		expect(body).toEqual({ ok: true });
+	});
+
+	it("should work with POST requests with trailing slash", async () => {
+		const { auth } = await getTestInstance({
+			advanced: {
+				skipTrailingSlashes: true,
+			},
+		});
+
+		// POST to sign-up endpoint with trailing slash
+		const response = await auth.handler(
+			new Request("http://localhost:3000/api/auth/sign-up/email/", {
+				method: "POST",
+				headers: { "Content-Type": "application/json" },
+				body: JSON.stringify({
+					email: "test2@example.com",
+					password: "password123",
+					name: "Test User 2",
+				}),
+			}),
+		);
+
+		// Should reach the endpoint (probably fail validation, but not 404)
+		expect(response.status).not.toBe(404);
+	});
+});

packages/better-auth/src/api/index.ts

@@ -273,6 +273,7 @@ export const router = <Option extends BetterAuthOptions>(
 			...middlewares,
 		],
 		allowedMediaTypes: ["application/json"],
+		skipTrailingSlashes: options.advanced?.skipTrailingSlashes ?? false,
 		async onRequest(req) {
 			//handle disabled paths
 			const disabledPaths = ctx.options.disabledPaths || [];

packages/core/src/types/init-options.ts

@@ -305,6 +305,12 @@ export type BetterAuthAdvancedOptions = {
 	backgroundTasks?: {
 		handler: (promise: Promise<void>) => void;
 	};
+	/**
+	 * Skip trailing slash validation in route matching
+	 *
+	 * @default false
+	 */
+	skipTrailingSlashes?: boolean | undefined;
 };
 
 export type BetterAuthOptions = {