“It works on my machine” becomes actionable when the browser request is attached. A HAR file preserves the network story: requests, responses, redirects, timing, and headers.
Short answer: export a HAR from browser DevTools' Network panel when diagnosing an HTTP issue that needs reproduction. Review it before sharing: cookies, authorization headers, query tokens, and response bodies can be inside.
| HAR field | Useful for |
|---|---|
| Request headers | CORS/auth differences |
| Redirect chain | Wrong URL or cache behavior |
| Timings | DNS, TLS, server, download delays |
A HAR is often a credential bundle disguised as a debug attachment. Sanitize it and use a secure support channel.
Use it to compare the failing browser request with the successful curl command. The difference is usually visible once both are concrete.
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