Testeur d'API

Send HTTP requests to any REST API and inspect the response - works with public endpoints and your localhost dev server

100 % gratuit. Cet outil a besoin de notre serveur pour effectuer le travail : ce que vous soumettez y est traité puis supprimé, il n'est jamais conservé.

Requests are sent directly from your browser first, so localhost and 127.0.0.1 endpoints work too - it falls back to a server-side proxy only if the browser can't reach the target directly (usually a CORS-blocked public API).

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Build a request on the left and hit Send to see the response here.

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À propos de cet outil

Build and send HTTP requests (GET, POST, PUT, DELETE, etc.) with custom headers, query parameters, and a request body, then inspect the full response - similar to lightweight Postman-style testing directly in your browser. Requests go out directly from your browser first, which is what makes testing your own localhost dev server possible - a server-hosted tool can never reach your machine, but your own browser can. If the browser can't complete a request directly (usually a public API blocking cross-origin requests), it automatically falls back to a server-side proxy so the request still goes through.

Flux de travail

Nettoyer et valider des données d'API

  1. 1Formater le JSONRendez-le lisible et repérez les erreurs de syntaxe.Ouvrir
  2. 2Convertir si nécessairePassez entre JSON, XML, YAML ou CSV.Ouvrir
  3. 3Comparer les versionsVoyez exactement ce qui a changé.Ouvrir
  4. 4Tester la requêteEnvoyez-la et inspectez la réponse.Vous êtes ici

Comment utiliser cet outil

  1. Choose HTTP method and URLPick GET/POST/PUT/DELETE and enter the exact endpoint you want to test.
  2. Add query params and headersSet required headers like Authorization and Content-Type plus any query string values.
  3. Provide body if neededFor POST/PUT/PATCH requests, paste JSON or other payload format expected by the API.
  4. Send and inspect responseReview status code, headers, and response body to validate behavior and debug quickly.

Pourquoi l’utiliser

  • Fast API debugging without installing external desktop clients.
  • Supports common request methods, headers, params, and payload testing.
  • Shows full response details for troubleshooting backend behavior.
  • Great for quick endpoint checks during frontend and backend development.

Usages courants

  • Testing REST endpoints during feature development.
  • Validating auth headers and token-based access flows.
  • Checking API error responses and edge-case behavior.
  • Verifying staging APIs before release or QA handoff.

Conseils pour de meilleurs résultats

  • Save sample payloads for repeat endpoint tests to speed up debugging.
  • Start with a simple GET to verify connectivity before complex body requests.
  • Match Content-Type exactly to your backend parser expectations.
  • Use realistic test data to reproduce production-like failures safely.

Erreurs à éviter

  • Forgetting auth headers and assuming the endpoint itself is broken.
  • Sending JSON with wrong Content-Type and misreading parse errors.
  • Ignoring response headers when debugging caching or CORS behavior.
  • Testing only success paths without checking error handling responses.

Questions fréquentes

You can add custom headers (including Authorization headers for tokens/API keys) to your request, so most authenticated APIs can be tested as long as you have valid credentials to include.

Requests are sent directly from your browser first, and some public APIs that don't allow cross-origin requests (no permissive CORS headers) will block that direct attempt - this tool then automatically retries the same request through a server-side proxy, so most public APIs still work even when the direct browser request is blocked.

Yes - because the request is sent directly from your own browser rather than from a remote server, it can reach http://localhost or 127.0.0.1 just like any other page open in your browser can. It still needs your local server to allow the request (CORS), which most dev frameworks permit by default in development.

Typically the response status code, headers, and body - letting you fully inspect what an endpoint actually returned, not just whether it succeeded.

Yes. API Tester is free for normal use with no account required, and ToolBox does not add a watermark to your result.

Most tools in this category run in your browser so the file stays on your device. If a tool needs a temporary server job, files are handled for that job only and are not kept as a lasting archive.

No install needed. Open API Tester in your browser, add your file or paste your input, then download or copy the result.

Yes on modern mobile browsers. For large files, a desktop browser is usually faster and more reliable.

Try a different quality or format setting, use a smaller input, or open a related tool (for example compress before convert). Keep a copy of the original file before replacing it.

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