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<h1 align="center">Fastify</h1> ## Middleware Starting with Fastify v3.0.0, middleware is not supported out of the box and requires an external plugin such as [`@fastify/express`](https://github.com/fastify/fastify-express) or [`@fastify/middie`](https://github.com/fastify/middie). An example of registering the [`@fastify/express`](https://github.com/fastify/fastify-express) plugin to `use` Express middleware: ```js await fastify.register(require('@fastify/express')) fastify.use(require('cors')()) fastify.use(require('dns-prefetch-control')()) fastify.use(require('frameguard')()) fastify.use(require('hsts')()) fastify.use(require('ienoopen')()) fastify.use(require('x-xss-protection')()) ``` [`@fastify/middie`](https://github.com/fastify/middie) can also be used, which provides support for simple Express-style middleware with improved performance: ```js await fastify.register(require('@fastify/middie')) fastify.use(require('cors')()) ``` Middleware can be encapsulated, allowing control over where it runs using `register` as explained in the [plugins guide](../Guides/Plugins-Guide.md). Fastify middleware does not expose the `send` method or other methods specific to the Fastify [Reply](./Reply.md#reply) instance. This is because Fastify wraps the incoming `req` and `res` Node instances using the [Request](./Request.md#request) and [Reply](./Reply.md#reply) objects internally, but this is done after the middleware phase. To create middleware, use the Node `req` and `res` instances. Alternatively, use the `preHandler` hook that already has the Fastify [Request](./Request.md#request) and [Reply](./Reply.md#reply) instances. For more information, see [Hooks](./Hooks.md#hooks). #### Restrict middleware execution to certain paths <a id="restrict-usage"></a> To run middleware under certain paths, pass the path as the first parameter to `use`. > ℹ️ Note: This does not support routes with parameters > (e.g. `/user/:id/comments`) and wildcards are not supported in multiple paths. ```js const path = require('node:path') const serveStatic = require('serve-static') // Single path fastify.use('/css', serveStatic(path.join(__dirname, '/assets'))) // Wildcard path fastify.use('/css/(.*)', serveStatic(path.join(__dirname, '/assets'))) // Multiple paths fastify.use(['/css', '/js'], serveStatic(path.join(__dirname, '/assets'))) ``` ### Alternatives Fastify offers alternatives to commonly used middleware, such as [`@fastify/helmet`](https://github.com/fastify/fastify-helmet) for [`helmet`](https://github.com/helmetjs/helmet), [`@fastify/cors`](https://github.com/fastify/fastify-cors) for [`cors`](https://github.com/expressjs/cors), and [`@fastify/static`](https://github.com/fastify/fastify-static) for [`serve-static`](https://github.com/expressjs/serve-static).