WS-Kit — Schema-First WebSocket Framework

Define message contracts with Zod or Valibot and get end-to-end TypeScript safety for WebSocket RPC and pub/sub across Bun, Cloudflare, Node.js, and browsers.

Docs → https://kriasoft.com/ws-kit/

Why WS-Kit

• Type inference from schema to handler, errors, and client calls
• RPC + pub/sub + middleware + lifecycle hooks in one router
• Pluggable validators/adapters (Bun, Cloudflare, Redis, in-memory)
• Test harness with fake connections, clock, and event capture
• Universal client with auto-reconnect, retries, and offline queueing

Install

# With Zod on Bun (recommended)
bun add @ws-kit/zod @ws-kit/bun
bun add zod bun @types/bun -D

# Valibot (smaller bundles)
bun add @ws-kit/valibot @ws-kit/bun
bun add valibot bun @types/bun -D

Quick start (server)

import { z, message, createRouter, withZod } from "@ws-kit/zod";
import { serve } from "@ws-kit/bun";

const Ping = message("PING", { text: z.string() });
const Pong = message("PONG", { reply: z.string() });

const router = createRouter().plugin(withZod());

router.on(Ping, (ctx) => {
  ctx.send(Pong, { reply: `Got: ${ctx.payload.text}` });
});

serve(router, {
  port: 3000,
  authenticate(req) {
    const token = req.headers.get("authorization");
    return token ? { userId: "u_123" } : undefined;
  },
});

Quick start (client)

import { rpc, message, wsClient } from "@ws-kit/client/zod";
import { z } from "@ws-kit/zod";

const Hello = rpc("HELLO", { name: z.string() }, "HELLO_OK", {
  text: z.string(),
});
const Broadcast = message("BROADCAST", { data: z.string() });

const client = wsClient({ url: "ws://localhost:3000" });
await client.connect();

const reply = await client.request(Hello, { name: "Ada" });
console.log(reply.payload.text); // typed as string

client.on(Broadcast, (msg) => {
  console.log(msg.payload.data);
});

More

• Docs: https://kriasoft.com/ws-kit/
• Examples: examples/
• Packages: packages/
• Support: Discord

Backers 💰

              

License

MIT