# bearerAuth

**Kind:** Function

**Source:** [`src/middleware/bearer-auth/index.ts`](https://github.com/honojs/hono/blob/main/src/middleware/bearer-auth/index.ts#L104)

**Part of:** [Middleware](subsystem-src-middleware)

Bearer Auth Middleware for Hono.

`bearerAuth` is Hono middleware that validates the Bearer token from an incoming request’s `Authorization` header. Apply it to routes or an app to reject requests with missing or invalid tokens before the route handler runs.

## Signature

```ts
function bearerAuth(options: BearerAuthOptions<E>): MiddlewareHandler<E>
```

## Parameters

| Name | Type |
|---|---|
| `options` | `BearerAuthOptions<E>` |

**Returns:** `MiddlewareHandler<E>`

## Diagram

```mermaid
graph LR
  Request[Incoming request] --> Middleware[bearerAuth middleware]
  Middleware --> Header[Authorization header]
  Header --> Token[Bearer token validation]
  Token -->|Valid| Handler[Route handler]
  Token -->|Missing or invalid| Unauthorized[Unauthorized response]
```

## Usage

```ts
import { Hono } from 'hono'
import { bearerAuth } from 'hono/bearer-auth'

const app = new Hono()

app.use(
  '/api/*',
  bearerAuth({
    token: 'my-secret-token',
  })
)

app.get('/api/profile', (c) => {
  return c.json({ message: 'Authenticated request' })
})

export default app
```

## AI Coding Instructions

- Apply `bearerAuth` before handlers that require authenticated requests.
- Pass the expected token with the `token` option, or provide token verification logic when authentication rules need custom validation.
- Send credentials through the `Authorization: Bearer <token>` request header.
- Scope middleware to protected route prefixes when public routes must remain accessible.

## Relationships

- IMPORTS → `HTTPException`
- IMPORTS → `timingSafeEqual`