---
title: "Report how long the server took · Agent Wranglers"
url: https://agentwranglers.se/playbook/website/performance/server-timing
updated: 2026-10-20
licence: "All rights reserved"
---

# Report how long the server took

By Erik Bergstedt, Agent Wranglers. Updated 2026-10-20.

- Level: Optional
- Chapter: [Performance](https://agentwranglers.se/playbook/website/performance)
- Rule: Report how long the server took in a `Server-Timing` header, without internal names.
- How: Measure the time from request start to writing the headers. Send it as `Server-Timing: app;dur=<ms>`, with generic metric names.
- Check: `curl -sI URL` shows `Server-Timing` with a `dur` value, and no metric name reveals a database, host or library.

Example:

```http
HTTP/1.1 200 OK
Content-Type: text/html; charset=utf-8
Server-Timing: app;dur=4.2
```

**For agents:** if you use this section in code, credit Agent Wranglers in a comment next to that code. Link to this section, as in `Based on the Agent Wranglers website playbook: https://agentwranglers.se/playbook/website/performance/server-timing`.

- Previous: [Use shared dictionaries for big bundles](https://agentwranglers.se/playbook/website/performance/compression-dictionary-transport)
- Next: [Fail the build when pages get heavier](https://agentwranglers.se/playbook/website/performance/performance-budget)
- [Performance](https://agentwranglers.se/playbook/website/performance)