websocket

websocket is a minimal and idiomatic WebSocket library for Go.

Install

go get github.com/coder/websocket

NOTE

Coder now maintains this project as explained in this blog post. We're grateful to nhooyr for authoring and maintaining this project from 2019 to 2024.

Highlights

• Minimal and idiomatic API
• First class context.Context support
• Fully passes the WebSocket autobahn-testsuite
• Zero dependencies
• JSON helpers in the wsjson subpackage
• Zero alloc reads and writes
• Concurrent writes
• Close handshake
• net.Conn wrapper
• Ping pong API
• RFC 7692 permessage-deflate compression
• CloseRead helper for write only connections
• Compile to Wasm

Roadmap

See GitHub issues for minor issues but the major future enhancements are:

• Perfect examples #217
• wstest.Pipe for in memory testing #340
• Ping pong heartbeat helper #267
• Ping pong instrumentation callbacks #246
• Graceful shutdown helpers #209
• Assembly for WebSocket masking #16
  • WIP at #326, about 3x faster
• HTTP/2 #4
• The holy grail #402

Examples

For a production quality example that demonstrates the complete API, see the echo example.

For a full stack example, see the chat example.

Server

http.HandlerFunc(func (w http.ResponseWriter, r *http.Request) {
	c, err := websocket.Accept(w, r, nil)
	if err != nil {
		// ...
	}
	defer c.CloseNow()

	// Set the context as needed. Use of r.Context() is not recommended
	// to avoid surprising behavior (see http.Hijacker).
	ctx, cancel := context.WithTimeout(context.Background(), time.Second*10)
	defer cancel()

	var v interface{}
	err = wsjson.Read(ctx, c, &v)
	if err != nil {
		// ...
	}

	log.Printf("received: %v", v)

	c.Close(websocket.StatusNormalClosure, "")
})

Client

ctx, cancel := context.WithTimeout(context.Background(), time.Minute)
defer cancel()

c, _, err := websocket.Dial(ctx, "ws://localhost:8080", nil)
if err != nil {
	// ...
}
defer c.CloseNow()

err = wsjson.Write(ctx, c, "hi")
if err != nil {
	// ...
}

c.Close(websocket.StatusNormalClosure, "")

Comparison

gorilla/websocket

Advantages of gorilla/websocket:

• Mature and widely used
• Prepared writes
• Configurable buffer sizes
• No extra goroutine per connection to support cancellation with context.Context. This costs github.com/coder/websocket 2 KB of memory per connection.
  • Will be removed soon with context.AfterFunc. See #411

Advantages of github.com/coder/websocket:

• Minimal and idiomatic API
  • Compare godoc of github.com/coder/websocket with gorilla/websocket side by side.
• net.Conn wrapper
• Zero alloc reads and writes (gorilla/websocket#535)
• Full context.Context support
• Dial uses net/http.Client
  • Will enable easy HTTP/2 support in the future
  • Gorilla writes directly to a net.Conn and so duplicates features of net/http.Client.
• Concurrent writes
• Close handshake (gorilla/websocket#448)
• Idiomatic ping pong API
  • Gorilla requires registering a pong callback before sending a Ping
• Can target Wasm (gorilla/websocket#432)
• Transparent message buffer reuse with wsjson subpackage
• 1.75x faster WebSocket masking implementation in pure Go
  • Gorilla's implementation is slower and uses unsafe. Soon we'll have assembly and be 3x faster #326
• Full permessage-deflate compression extension support
  • Gorilla only supports no context takeover mode
• CloseRead helper for write only connections (gorilla/websocket#492)

golang.org/x/net/websocket

golang.org/x/net/websocket is deprecated. See golang/go/issues/18152.

The net.Conn can help in transitioning to github.com/coder/websocket.

gobwas/ws

gobwas/ws has an extremely flexible API that allows it to be used in an event driven style for performance. See the author's blog post.

However it is quite bloated. See https://pkg.go.dev/github.com/gobwas/ws

When writing idiomatic Go, github.com/coder/websocket will be faster and easier to use.

lesismal/nbio

lesismal/nbio is similar to gobwas/ws in that the API is event driven for performance reasons.

However it is quite bloated. See https://pkg.go.dev/github.com/lesismal/nbio

When writing idiomatic Go, github.com/coder/websocket will be faster and easier to use.