# Bun Metrics

> Monitor server activity with built-in metrics

- Skill: `jarle/bun-metrics` (Agent Skill)
- Install (CLI): `npx skillmds@latest add jarle/bun-metrics`
- Raw SKILL.md: https://api.skillmd.com/api/skills/jarle/bun-metrics/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: jarle (https://skillmd.com/u/jarle)
- Updated: 2026-09-10
- Page: https://skillmd.com/skills/jarle/bun-metrics

---


# Metrics

> Monitor server activity with built-in metrics

### `server.pendingRequests` and `server.pendingWebSockets`

Monitor server activity with built-in counters:

```ts  theme={"theme":{"light":"github-light","dark":"dracula"}}
const server = Bun.serve({
  fetch(req, server) {
    return new Response(
      `Active requests: ${server.pendingRequests}\n` + `Active WebSockets: ${server.pendingWebSockets}`,
    );
  },
});
```

### `server.subscriberCount(topic)`

Get count of subscribers for a WebSocket topic:

```ts  theme={"theme":{"light":"github-light","dark":"dracula"}}
const server = Bun.serve({
  fetch(req, server) {
    const chatUsers = server.subscriberCount("chat");
    return new Response(`${chatUsers} users in chat`);
  },
  websocket: {
    message(ws) {
      ws.subscribe("chat");
    },
  },
});
```