Fault Injection API — free mock REST API for testing

Configure deterministic network and server failures inside your isolated sandbox.

The Fault Injection API turns failure into a setting. Configure a target — latency, a status code, a malformed body, or a flaky success rate — then call it and get exactly that. It is the catalog's tool for testing resilience deliberately instead of waiting for production to supply the outage.

Base URL: https://funapi.dev/api/faults/v1 · 4 endpoints · OpenAPI 3.1 spec and Postman collection available. New here? Read the getting started guide.

What you can practise here

• Set a 50% failure rate and check that your retry policy converges instead of amplifying the load.
• Inject a malformed JSON body and confirm your client reports a parse error rather than crashing.
• Inject latency just above your timeout, then just below, and verify the boundary behaves as designed.
• Configure a 503 with Retry-After and check your backoff honours the header instead of guessing.

control

fault profile

• GET /faults/v1/config — Read fault profile · Responds with 200 Link to this endpoint
• PUT /faults/v1/config — Configure fault profile (requires Bearer auth) · Responds with 200 422 Link to this endpoint
• DELETE /faults/v1/config — Reset fault profile (requires Bearer auth) · Responds with 204 Link to this endpoint

target

endpoint under test

• GET /faults/v1/target — Call the configured flaky target · Responds with 200 500 503 Link to this endpoint

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• Protocol Lab API — Async jobs, redirects, 503/504, JSON Patch & content negotiation.
• Object Storage API — Objects, checksums, ranges & resumable uploads.

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