@fastify/websocket review
A focused, open-source plugin for adding route-level WebSocket handling to Fastify.
Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
For developers building Fastify applications, @fastify/websocket adds WebSocket handling to routes rather than providing a hosted service. Routes can accept WebSocket connections, and handlers receive the socket and request so they can process messages and send responses. The plugin is open source, distributed as an npm package, and includes TypeScript types. Its focused role suits teams that want WebSocket behavior inside a Fastify app; it is less suited to buyers seeking a standalone messaging platform.
The integration follows Fastify's route and hook model. Developers can define route-specific handlers, use wildcard WebSocket routes, or configure a shared handler. Fastify request hooks run before a connection is upgraded, and the documentation notes they can be used for request processing such as authentication. The plugin is built on the `ws` package and allows WebSocket server options to be configured, including maximum payload size. This gives Fastify developers a route-level way to connect request processing with socket handling, while keeping the scope centered on WebSocket connections rather than a wider application messaging stack.
The main trade-off is that this is an integration for Fastify, not a general-purpose solution across frameworks. Its documented focus is WebSocket handling; it does not provide pub/sub messaging, so teams that need that layer should consider a broader messaging product. It is also a library to run within an application rather than a managed service, making it a better fit for developers who can work with Fastify and their own deployment. The open-source model suits teams looking to add this capability without a paid plan. Choose it when route-level WebSockets belong in a Fastify app; look elsewhere if you need framework-independent service hosting or a messaging platform.
@fastify/websocket pros and cons
- Where it wins
- Adds route-specific and wildcard WebSocket handling to Fastify routes
- Runs Fastify request hooks before a WebSocket connection is established
- Includes TypeScript types and configurable WebSocket server options
- Where it doesn't
- Designed for Fastify rather than general-purpose WebSocket applications
- Provides WebSocket handling, not a pub/sub messaging layer
- A self-hosted library, not a managed WebSocket service
@fastify/websocket fact sheet, pricing and score →
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