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API Contract Tester

Online API contract tester for request execution, response checks, contract assertions, and stress tests in integration and regression workflows.

This tool sends real network requests to the URL you provide. Verify endpoint, headers, and payload before execution.

Request Configuration

Authentication

Request Headers

Response

Response data will appear here after sending request

Contract Validation

Stress Test

Request History



Documentation

About API Contract Tester

This tool sends HTTP requests and validates whether responses satisfy expected API contracts, with auth options and basic stress testing.

Key Features

  • Request Builder: Configure method, URL, headers, and body.
  • Auth Support: Bearer, Basic, API Key, and OAuth2 modes.
  • Response Viewer: Inspect status, latency, headers, and body.
  • Contract Validation: Validate fields, types, and structure rules.
  • Stress Test: Run lightweight concurrency/duration checks.

Steps

  1. Configure request method, URL, headers, and body.
  2. Set authentication parameters if needed.
  3. Send request and inspect response details.
  4. Define contract rules and run validation.
  5. Optionally run stress test for stability signals.

Use Cases

  • API integration validation during development.
  • Contract consistency checks in regression.
  • Pre-release smoke performance checks.

FAQ

Why do I get CORS or request errors?

Browser requests are limited by CORS and network policies. Ensure the target service allows your origin.

How should I write contract rules?

Start with critical checks: status code, required fields, and data types, then add business constraints.