---
description: Allow or deny a request based on a known pre-shared key in a header. This is not meant to replace the WebCrypto API.
title: Auth with headers
image: https://developers.cloudflare.com/og-docs.png
---

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# Auth with headers

Allow or deny a request based on a known pre-shared key in a header. This is not meant to replace the WebCrypto API.

Last updated Aug 24, 2026|Copy as Markdown|[View as Markdown](https://9a51ac8b.previews.developers.cloudflare.com/workers/examples/auth-with-headers/index.md)|[Agent setup](https://9a51ac8b.previews.developers.cloudflare.com/agent-setup/)

Caution when using in production

The example code contains a generic header key and value of `X-Custom-PSK` and `mypresharedkey`. To best protect your resources, change the header key and value in the Workers editor before saving your code.

```js
export default {
	async fetch(request) {
		/**
		 * @param {string} PRESHARED_AUTH_HEADER_KEY Custom header to check for key
		 * @param {string} PRESHARED_AUTH_HEADER_VALUE Hard coded key value
		 */
		const PRESHARED_AUTH_HEADER_KEY = "X-Custom-PSK";
		const PRESHARED_AUTH_HEADER_VALUE = "mypresharedkey";
		const psk = request.headers.get(PRESHARED_AUTH_HEADER_KEY);

		if (psk === PRESHARED_AUTH_HEADER_VALUE) {
			// Correct preshared header key supplied. Fetch request from origin.
			return fetch(request);
		}

		// Incorrect key supplied. Reject the request.
		return new Response("Sorry, you have supplied an invalid key.", {
			status: 403,
		});
	},
};
```

```ts
export default {
	async fetch(request): Promise<Response> {
		/**
		 * @param {string} PRESHARED_AUTH_HEADER_KEY Custom header to check for key
		 * @param {string} PRESHARED_AUTH_HEADER_VALUE Hard coded key value
		 */
		const PRESHARED_AUTH_HEADER_KEY = "X-Custom-PSK";
		const PRESHARED_AUTH_HEADER_VALUE = "mypresharedkey";
		const psk = request.headers.get(PRESHARED_AUTH_HEADER_KEY);

		if (psk === PRESHARED_AUTH_HEADER_VALUE) {
			// Correct preshared header key supplied. Fetch request from origin.
			return fetch(request);
		}

		// Incorrect key supplied. Reject the request.
		return new Response("Sorry, you have supplied an invalid key.", {
			status: 403,
		});
	},
} satisfies ExportedHandler;
```

```py
from workers import WorkerEntrypoint, Response, fetch

class Default(WorkerEntrypoint):
    async def fetch(self, request):
        PRESHARED_AUTH_HEADER_KEY = "X-Custom-PSK"
        PRESHARED_AUTH_HEADER_VALUE = "mypresharedkey"

        psk = request.headers[PRESHARED_AUTH_HEADER_KEY]

        if psk == PRESHARED_AUTH_HEADER_VALUE:
            # Correct preshared header key supplied. Fetch request from origin.
            return fetch(request)

        # Incorrect key supplied. Reject the request.
        return Response("Sorry, you have supplied an invalid key.", status=403)
```

```ts
import { Hono } from 'hono';

const app = new Hono();

// Add authentication middleware
app.use('*', async (c, next) => {
  /**
   * Define authentication constants
   */
  const PRESHARED_AUTH_HEADER_KEY = "X-Custom-PSK";
  const PRESHARED_AUTH_HEADER_VALUE = "mypresharedkey";

  // Get the pre-shared key from the request header
  const psk = c.req.header(PRESHARED_AUTH_HEADER_KEY);

  if (psk === PRESHARED_AUTH_HEADER_VALUE) {
    // Correct preshared header key supplied. Continue to the next handler.
    await next();
  } else {
    // Incorrect key supplied. Reject the request.
    return c.text("Sorry, you have supplied an invalid key.", 403);
  }
});

// Handle all authenticated requests by passing through to origin
app.all('*', async (c) => {
  return fetch(c.req.raw);
});

export default app;
```

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