# Effect Integration (/docs/integrations/effect)

Integrate Better Auth with an Effect HTTP server.



Better Auth uses Web Standard `Request` and `Response` objects. Effect 4 can mount `auth.handler` with `HttpEffect.fromWebHandler`.

Before you begin, [configure a Better Auth instance](/docs/installation).

## Install Effect [#install-effect]

<CodeBlockTabs defaultValue="npm" groupId="persist-install">
  <CodeBlockTabsList>
    <CodeBlockTabsTrigger value="npm">
      npm
    </CodeBlockTabsTrigger>

    <CodeBlockTabsTrigger value="pnpm">
      pnpm
    </CodeBlockTabsTrigger>

    <CodeBlockTabsTrigger value="yarn">
      yarn
    </CodeBlockTabsTrigger>

    <CodeBlockTabsTrigger value="bun">
      bun
    </CodeBlockTabsTrigger>
  </CodeBlockTabsList>

  <CodeBlockTab value="npm">
    ```bash
    npm install effect
    ```
  </CodeBlockTab>

  <CodeBlockTab value="pnpm">
    ```bash
    pnpm add effect
    ```
  </CodeBlockTab>

  <CodeBlockTab value="yarn">
    ```bash
    yarn add effect
    ```
  </CodeBlockTab>

  <CodeBlockTab value="bun">
    ```bash
    bun add effect
    ```
  </CodeBlockTab>
</CodeBlockTabs>

If you're starting a new Effect project, follow the [Effect installation guide](https://effect.website/docs/v4/getting-started/installation#javascript-runtimes).

## Mount the auth handler [#mount-the-auth-handler]

The example below runs on Node.js. See the [Effect Platform guide](https://effect.website/docs/v4/platform/introduction) to use another runtime.

<CodeBlockTabs defaultValue="npm" groupId="persist-install">
  <CodeBlockTabsList>
    <CodeBlockTabsTrigger value="npm">
      npm
    </CodeBlockTabsTrigger>

    <CodeBlockTabsTrigger value="pnpm">
      pnpm
    </CodeBlockTabsTrigger>

    <CodeBlockTabsTrigger value="yarn">
      yarn
    </CodeBlockTabsTrigger>

    <CodeBlockTabsTrigger value="bun">
      bun
    </CodeBlockTabsTrigger>
  </CodeBlockTabsList>

  <CodeBlockTab value="npm">
    ```bash
    npm install @effect/platform-node
    ```
  </CodeBlockTab>

  <CodeBlockTab value="pnpm">
    ```bash
    pnpm add @effect/platform-node
    ```
  </CodeBlockTab>

  <CodeBlockTab value="yarn">
    ```bash
    yarn add @effect/platform-node
    ```
  </CodeBlockTab>

  <CodeBlockTab value="bun">
    ```bash
    bun add @effect/platform-node
    ```
  </CodeBlockTab>
</CodeBlockTabs>

```ts title="src/index.ts"
import { createServer } from "node:http";
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node";
import { Layer } from "effect";
import { HttpEffect, HttpRouter, HttpServerResponse } from "effect/http";
import { auth } from "./auth.ts";

const homeRoute = HttpRouter.add(
  "GET",
  "/",
  HttpServerResponse.text("Hello Better Auth"),
);

const authRoutes = HttpRouter.add( // [!code highlight]
  "*", // [!code highlight]
  "/api/auth/*", // Match your Better Auth basePath. // [!code highlight]
  HttpEffect.fromWebHandler(auth.handler), // [!code highlight]
); // [!code highlight]

const routes = Layer.mergeAll(homeRoute, authRoutes);

const server = HttpRouter.serve(routes).pipe(
  Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 })),
);

Layer.launch(server).pipe(NodeRuntime.runMain);
```

## Cross-origin requests [#cross-origin-requests]

If your frontend runs on a different origin, allow it in both the Effect server's CORS middleware and Better Auth's `trustedOrigins`. The middleware applies to every route, so list only the origins that need cookie access.

```ts title="src/auth.ts"
import { betterAuth } from "better-auth";

export const auth = betterAuth({
  trustedOrigins: ["http://localhost:5173"], // [!code highlight]
});
```

```ts title="src/index.ts"
import { HttpMiddleware } from "effect/http";

const server = HttpRouter.serve(routes, {
  middleware: HttpMiddleware.cors({
    allowedOrigins: ["http://localhost:5173"], // [!code highlight]
    credentials: true,
  }),
}).pipe(
  Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 })),
);
```

For cross-site cookies, see [Cookies](/docs/concepts/cookies).

## Protect application routes [#protect-application-routes]

You can protect application resources by checking the session with Better Auth:

```ts title="src/index.ts"
import { Effect } from "effect";
import { HttpServerRequest, HttpServerResponse } from "effect/http";

const profileRoute = HttpRouter.add(
  "GET",
  "/profile",
  Effect.gen(function* () {
    const request = yield* HttpServerRequest.HttpServerRequest;
    const session = yield* Effect.tryPromise(() =>
      auth.api.getSession({ headers: request.headers }),
    );

    if (!session) {
      return HttpServerResponse.empty({ status: 401 });
    }

    return yield* HttpServerResponse.json(session.user);
  }),
);

const routes = Layer.mergeAll(homeRoute, authRoutes, profileRoute);
```