Keploy
Keploy automatically creates and replays API tests from application traffic, capturing external dependencies to help developers detect unexpected behaviour changes.
Why it caught my attention
Creating realistic tests is often harder than writing the application code itself. Keploy approaches this differently: instead of starting with test scripts, it captures how an application actually behaves. That makes it particularly interesting for teams maintaining existing APIs with limited automated regression coverage.
What problem does this actually solve?
Keploy could be worth considering if you recognise any of these challenges.
Writing tests takes too long
Recording real API requests creates reusable tests, reducing the need to script every scenario from scratch.
Code changes break existing behaviour
Replaying captured requests helps reveal unexpected response changes before updated services reach users.
Testing depends on external services
Recorded database and API interactions can replace supported live dependencies, making repeatable tests easier to run.
Existing systems lack regression coverage
Capturing current behaviour provides a testing baseline for legacy services, migrations and application rewrites.
Is this a good fit for you?
A quick way to see if Keploy is relevant for your situation.
- You develop or maintain backend APIs that change regularly.
- Your team spends significant time writing and maintaining regression tests.
- You want to test services without keeping every external dependency running.
- You maintain legacy applications with limited existing automated test coverage.
- You want repeatable API checks within your CI/CD pipelines.
- Your main requirement is visual testing of frontend interfaces.
- You primarily need isolated unit tests for internal application logic.
How does it work?
In practice, the workflow looks something like this:
Install the appropriate version for your operating system, authenticate where required and configure it to launch your application.
Start recording, then exercise your API through normal requests while Keploy captures responses and supported external dependency interactions.
Keploy stores captured requests and dependency mocks as readable test artefacts that developers can inspect and maintain.
Run recorded requests against the updated application, using captured dependency responses and comparing actual results with expected behaviour.
Run the tests through supported CI/CD tools, investigate failures and refresh recordings when intended application behaviour changes.
What else should I know?
A few important things to be aware of before you investigate further.
Platform support varies
Linux uses eBPF; native macOS and Windows capture supports fewer languages and protocols. Check your environment carefully.
Recorded behaviour defines the baseline
Captured tests check previously observed behaviour. Additional tests remain necessary for unrecorded edge cases and requirements.
Authentication and usage allowances
Current recording and replay commands require a Keploy account, with free-tier allowances and paid features varying by plan.
Captured traffic needs careful handling
Tests and mocks may contain sensitive request data. Review sanitisation and storage arrangements before recording production-like traffic.
Think Keploy could fit your environment?
Visit the Keploy website to find out more, request a demo or speak to their team.
Something you'd like to know about Keploy?
Is there something I haven't covered in my research? Send me your question and I'll look into it and reply personally by email.