API Endpoint Tester

Server assisted API Testing

Enter a public URL and get an instant smoke test: HTTP status, latency breakdown, response size, content type, server headers and redirect behaviour.

Privacy: This tool sends the request through the Mutqan backend relay to reach the target. Only the target URL, headers and body you enter are transmitted, and nothing is stored.

What is API testing?

API testing checks a service through its interface rather than its screens: send a request with a chosen method, headers and body, then verify the status code, the response headers, the body's structure and values, and the time it took. Because it runs below the UI, it is faster, more stable and catches integration defects earlier — which is why regression suites are built API-first.

Read the guide: What is API Testing? How to Test a REST API

How to use API Endpoint Tester

  1. Paste the endpoint URL (public http/https).
  2. Optionally choose a method, disable redirect following or add headers such as Authorization.
  3. Run the test and read the stats, the details panel and the header table.
  4. Download the headers as CSV or the body preview for a bug report.

API Endpoint Tester features

  • One-click smoke test: status, total time, time-to-first-byte, size and content type
  • HEAD support check, redirect chain, final URL and TLS/HSTS observations
  • Caching, compression, CORS and rate-limit headers surfaced with explanations
  • Header table with plain-language meaning for every header
  • Body preview with automatic JSON/XML/HTML pretty-printing

API Endpoint Tester example

Smoke-test a JSON endpoint

Input:

https://httpbin.org/get?ping=1

Output:

Status 200 · Total 380 ms (TTFB 210 ms) · 420 B · application/json
Reachable: Yes · TLS: HTTPS (no HSTS) · Server: gunicorn/19.9.0 · CORS: * · HEAD support: 200 in 190 ms

Frequently asked questions about API Endpoint Tester

What does the smoke test check?

It sends a HEAD and then a GET (or the method you choose) through the relay and reports status, total time and time-to-first-byte, size, content type, TLS/HSTS, redirects, caching, compression, CORS and rate-limit headers.

Can I test endpoints that need a token?

Yes — add an Authorization header in the extra headers field. Headers are used for this run only and are not stored.

Why is the body preview cut off?

The preview shows at most 20 000 characters so the page stays responsive; download the body output for the full text (the relay itself caps very large bodies).

Can it reach internal or localhost URLs?

No. The relay only reaches public http(s) endpoints. For local services use the API Request Builder in direct-browser mode.

Technical notes

For GET requests a HEAD request is attempted first to measure header-only latency and confirm HEAD support, then the real request is sent. Both go through the relay, which stops waiting after 15 seconds.

References

  • RFC 9110: HTTP SemanticsIETF · 2022The meaning of HTTP methods, header fields, status codes and content negotiation, independent of the wire version.
  • OpenAPI SpecificationOpenAPI InitiativeThe standard for describing REST APIs: paths, operations, parameters, schemas, responses and security schemes.
  • OWASP Cheat Sheet Series: REST SecurityOWASP FoundationSecurity rules for REST APIs: HTTPS, authentication on every request, input validation, safe error responses, rate limiting.