Your first API contract
Create a task, inspect its representation, and learn how the API explains an invalid request.
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Practice requests, understand failures, and verify your solutions.
Create a task, inspect its representation, and learn how the API explains an invalid request.
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Your progress comes from server-verified results.Begin with requests and responses. Build up to reliable integrations.
Create a task, inspect its representation, and learn how the API explains an invalid request.
Read a resource, inspect headers without a body, discover allowed methods, and distinguish a missing record from an empty collection.
Change one field with PATCH, see why an incomplete PUT fails, then replace the full representation.
Retrieve five catalog items across three pages. Follow next_offset, then inspect an empty page and an invalid page size.
Create a temporary task, delete it, and confirm it is gone. Learn why a successful 204 has no JSON body and a repeated delete can return 404.
Observe a simulated 401, distinguish it from a missing resource, and retry after clearing credential expiry. This lab simulates expiry; it does not rotate a real token.
Create an order, pay once despite a retry, then move it to delivered. Watch the stored state and response headers at each step.
Retry the same booking with one idempotency key, then observe the conflict when that key is reused for a different payload.
Read inventory in pages, detect a stale update, and safely change stock using the current ETag.
Inspect Retry-After after a simulated rate limit, advance the virtual clock, and recover. Repeat after a simulated timeout; virtual time never measures a real network wait.
Compare a collection returned as items with the expected data envelope. Preserve both responses as evidence, then restore the expected contract.
Accept unique event IDs, reject a duplicated event, and recover from an injected service outage before activating a subscription.
Keep useful attempts for comparison. Delete old attempts when you reach the 20-attempt limit.
Start a capstone to create your first saved attempt.