API Error Decoder

Debug HTTP errors instantly. Capture 4xx, 5xx, CORS & network failures, replay requests, and export to Postman — right in DevTools.

API Error Decoder — Debug HTTP Failures Instantly Stop guessing why your API calls fail. API Error Decoder captures every 4xx, 5xx, network, and auth error in real time — right inside Chrome DevTools. How it works Click Start Capture, browse or interact with your page, and failed requests appear automatically. No manual filtering. No console spelunking. Click any failure to see headers, request body, response body, and a plain-English diagnosis. Free features - Capture 4xx, 5xx, auth (401/403), validation (422), rate-limit (429), and network failures - Instant diagnosis: understand exactly why each request failed - Filter by error type: Auth, Validation, Rate Limit, Network, and more - Toggle: first-party only, deduplicate repeated failures Pro features (one-time payment) - Replay — re-send any captured request directly from the panel - JWT Inspector — decode and inspect JWT tokens in request headers - Export — download as cURL command, Postman collection, or JSON debug package - Session History — browse and reload past capture sessions Who it's for - Frontend developers debugging API integrations - Full-stack engineers tracking down backend errors - QA engineers reproducing flaky failures - No account required to start. Install, open DevTools, and capture your first failure in seconds. Support: https://100plus.tools/extensions/api-error-decoder/support Privacy Policy: https://100plus.tools/extensions/api-error-decoder/privacy Terms of Service: https://100plus.tools/extensions/api-error-decoder/terms