Integrating WebSocket Services in a Serverless World

Serverless functions (like Next.js API routes deployed to Vercel, AWS Lambda, or similar platforms) are designed to be stateless and short-lived. Each invocation boots, handles a request, and terminates.

WebSockets, on the other hand, require a persistent, long-lived TCP connection between client and server. This creates a fundamental mismatch:

• Serverless runtimes have execution time limits (e.g. 10–30 seconds).
• There is no persistent process to hold an open socket across requests.
• Horizontal scaling means each new instance has no shared in-memory state.

The solution is to delegate real-time communication to a managed WebSocket provider — a dedicated service that maintains connections on your behalf while your serverless functions focus on business logic.

Managed WebSocket providers expose an HTTP API that your serverless functions can call to push messages into persistent connections they maintain. Popular options include:

• Pusher / Pusher Channels — battle-tested, generous free tier, first-class Next.js support.
• Ably — low-latency pub/sub with edge-friendly token auth.
• Soketi — open-source, self-hosted Pusher-compatible server.
• PartyKit — built specifically for Next.js and Cloudflare Workers.

The typical flow is:

• Client connects to the provider's WebSocket endpoint and subscribes to a channel.
• Your Next.js Server Action or Route Handler calls the provider's REST API to publish an event.
• The provider fans the event out to all subscribed clients instantly.

Your serverless function never touches a socket directly — it simply makes an HTTP POST.