ProxyCeptor for QA Engineers: Test Every API Failure Without Waiting on Backend
QA engineers use ProxyCeptor to create repeatable API scenarios, such as "checkout returns 503", "orders list is empty" or "profile loads in 8 seconds", as named rules they toggle in one click. Rules run in Chrome and on Smart TVs without certificates, sync across the QA team through a cloud workspace, and pair with session replay for bug reports.
Problems qa engineers run into
Waiting on backend to reproduce edge cases
Getting staging to return a 429 or an empty list usually means a ticket to another team and a day of waiting.
Bugs that cannot be reproduced
The customer saw a broken screen with specific data, and staging has different data.
Device labs without certificate access
Smart TVs and locked test devices cannot trust a Charles or Fiddler root certificate.
Bug reports without context
Developers ask "what did the API return?" and the tester no longer has it.
Workflows that fix them
Build a scenario library
Create one rule per scenario ("Payments 503", "Cart empty", "Session expired") in a shared workspace. Anyone on the team can toggle it; nobody writes JSON twice.
Negative testing on demand
Force 4xx and 5xx responses, add latency, or null a single field with deep merge while the rest of the payload stays live. Work through the 25-case error checklist.
Reproduce customer bugs exactly
Take the payload from a customer's HAR file and mock it for the affected endpoint. You now see exactly what they saw.
Better bug reports
Record the session with the built-in rrweb replay and export a self-contained HTML report with DOM, console and network events in sync. See recording and replaying sessions.
Example
{ "name": "QA: Orders empty", "match": { "urlPattern": "*/api/v2/orders*", "matchType": "wildcard" }, "response": { "body": { "enabled": true, "mode": "replace-whole", "statusCode": 200, "value": "{ \"items\": [], \"total\": 0 }" } }}Frequently asked questions
Do testers need to write code?
No. Rules are created in a form in the DevTools panel or dashboard. JSON is optional, for people who prefer copy and paste.
Can we use it for exploratory testing on Smart TVs?
Yes. Add the SDK to the TV test build with a workspace API key; rules toggled in the dashboard reach the TV on its next refresh. See the Smart TV use case.
Does it replace our automated test mocks?
No. Keep automated tests on code-level mocks. ProxyCeptor covers manual, exploratory and device testing, and demos.
Related guides
Try these workflows free
Create a free ProxyCeptor account to mock, delay, block and rewrite API traffic, then share the same rules with your team.