Protocol Lab API — free mock REST API for testing

Protocol mechanics the themed APIs do not cover: 202 Accepted with job polling, 301/302 redirects (and a chain), 503 with Retry-After, a guaranteed 504, Accept-based content negotiation with 406, HATEOAS links, RFC 6902 JSON Patch and 410 Gone.

The Protocol Lab is the catalog's HTTP semantics bench, and covers what most mock APIs never do: 202-accepted async jobs you poll to completion, 301 and 302 redirects, 503 and 504 outages, JSON Patch, and content negotiation that answers 406 when it cannot satisfy your Accept header. If a client library is going to surprise you, it will surprise you here.

Base URL: https://funapi.dev/api/protocol/v1 · 12 endpoints · OpenAPI 3.1 spec and Postman collection available. New here? Read the getting started guide.

What you can practise here

• Start a job, follow the 202 and its Location header, and poll until it completes.
• Follow a 301 and a 302 and check whether your HTTP client preserves the method and the body.
• Send an Accept header the server cannot satisfy and read the 406.
• Apply a JSON Patch document, then one whose test operation fails, and compare the results.
• Trigger the 503 and 504 endpoints to confirm your timeout and retry policy behaves as designed.

jobs

202 Accepted + poll to completion

• POST /protocol/v1/jobs — Start an async job — 202 Accepted
• GET /protocol/v1/jobs/{id} — Poll a job — progresses on every poll

redirects

301, 302 and a chain to follow

• GET /protocol/v1/moved/old-dashboard — Permanently moved — 301
• GET /protocol/v1/moved/new-dashboard — Where the 301 leads
• GET /protocol/v1/hop — A 302 redirect chain — follow it down

outages

503 & 504 on demand

• GET /protocol/v1/maintenance — Scheduled maintenance — 503 + Retry-After
• GET /protocol/v1/gateway-timeout — Slow upstream — waits ~3s, then 504

documents

HATEOAS, JSON Patch, 406 & 410

• GET /protocol/v1/export/documents — Content negotiation via Accept (406 on anything else)
• GET /protocol/v1/documents — List documents (HATEOAS links)
• GET /protocol/v1/documents/{id} — Get a document (410 after deletion)
• PATCH /protocol/v1/documents/{id} — RFC 6902 JSON Patch (op/path/value)
• DELETE /protocol/v1/documents/{id} — Delete a document (admin only, then 410) (requires Bearer auth)

Related APIs

• Auth Playground API — OAuth 2.0 flows — client credentials, auth code, refresh & expiry.
• Webhooks API — Register callbacks, trigger events, inspect & replay deliveries.
• Object Storage API — Objects, checksums, ranges & resumable uploads.
• Modern Identity API — OIDC discovery, PKCE, device codes & token lifecycle.

All 39 mock REST APIs