api-medic by Mark Marquez

api-medic is an open-source HTTP API troubleshooting tool that adds an "api-medic" panel to Firefox DevTools. It's built for support engineers, SREs, and developers who need to quickly diagnose customer-reported API issues, but works on any HTTP request.

How it works:
Open DevTools and select the api-medic tab.
Pick a request from the Network panel.
Send it for analysis. The panel transmits that single request — wrapped as a one-entry HAR — to the hosted analyzer and renders the returned diagnostic Report inline.

What it checks:
TLS configuration and certificate issues
Redirect chains and redirect loops
Authentication and authorization headers
Content negotiation (Accept, Content-Type, charset, encoding)
Rate-limit headers (Retry-After, X-RateLimit-*, etc.)
CORS, caching, and other common HTTP misconfigurations

Privacy:
Stateless backend: no database writes, no telemetry.
Only the single request you select is transmitted, only when you click to analyze.
The hosted analyzer accepts requests only from this extension's origin.
Source code (extension and Lambda backend): https://github.com/marky224/api-medic