What Hoverfly Can’t Test, Keploy Cancatch what breaks
Auto-Generated Tests from Traffic vs Proxy-Based Service Virtualization
Keploy uses eBPF to capture real production traffic and auto-generate both regression tests and mocks with zero code changes. Hoverfly is a lightweight Go proxy that sits between your app and external services to capture and simulate their responses for service virtualization. Keploy focuses on generating a full test suite from real behavior; Hoverfly focuses on standing in for slow or unreliable third-party dependencies during testing.
eBPF · zero code changesHow Keploy turns real traffic into a test suite
One pipeline, running the moment your app receives a request. No SDKs, no sidecars, no test scripts — just kernel-level capture that becomes deterministic regression coverage.
- 01Real API trafficLive requests + responses from your running app
- 02eBPF captureKernel-level recording — zero code changes
- 03NormalizeTime-freeze + field noise removed automatically
- 04Generate testsDeterministic test cases from actual behavior
- 05Generate mocksEvery downstream dependency stubbed for you
- 06Replay in CIRuns locally, in CI, or in-cluster on Kubernetes
- 07Regression detectionDiffs flagged before they reach production
See how the capture-replay engine works under the hood.
Trusted by engineering teams at scale
Why teams switch from Hoverfly
Keploy eliminates manual test authoring by generating tests automatically from real traffic — no scripts, no stubs, no infrastructure setup.
Want to auto-generate a full regression test suite, not just simulate dependencies
Need mocks for databases and internal services, not only external HTTP APIs
Prefer eBPF capture with no proxy configuration or certificate management
The numbers behind the switch
Industry data on how much manual testing costs teams — and what Keploy delivers from the first recording session.
Writing tests, configuring mocks, debugging flakiness — not building features that ship.
A routine rename or interface change silently invalidates more than half your suite.
Keploy generates tests from every request your API actually handles — no guessing.
Traffic capture reaches edge cases, error paths, and concurrent requests no dev would write.
Pain stats sourced from developer productivity surveys. Coverage stats from Keploy production recording sessions across 50+ engineering teams.
Every number here comes from teams running Keploy in CI.
Zero code. Real tests. Automatically.
Keploy's eBPF agent intercepts every API call at the kernel level and turns live traffic into test cases with dependency mocks — no SDK, no sidecars, no annotations.
Incoming API Requests
Keploy Agentrecording · analyzing · generatingEvery API call your app makes gets captured, replayed as a test, and its dependencies auto-mocked — continuously, from real traffic.
How they compare, dimension by dimension
A logical breakdown across the dimensions that matter. Click any row for real-world KPI impact across industries.
Auto-generates full regression tests from captured traffic
No test-case generation — provides simulated responses only
Zero code changes — captures via eBPF at kernel level
No code changes, but requires routing traffic through the proxy
Auto-generates mocks for all downstream dependencies
Captures and simulates external HTTP/HTTPS dependency responses
Built-in time-freezing and field normalization
Manual editing of simulation JSON or middleware scripts
HTTP, gRPC, and many DB/queue protocols captured at network level
HTTP and HTTPS via proxy
Native CLI integration with any CI pipeline
CLI and Docker image runnable in CI pipelines
KeployClick any dimension to see real-world KPI impact across industries.
Dive into how each capability actually works.
Your tests miss more than you think
Manual tests cover paths developers remember to write — usually just the happy path. Keploy captures every pattern production traffic actually generates.
Coverage grid shows 8 common endpoints × 10 production scenario types. Manual tests cover only what developers remember to write. Keploy captures every pattern your API actually serves in production.
Keploy is open source — read the code that captures this coverage.
The infrastructure you're maintaining
Traditional testing stacks require a shadow infrastructure to exist alongside your real app. Keploy eliminates all of it — tests and mocks come from actual traffic, not from services you run and maintain.
How they work differently
Architectural differences that affect workflow, cost, and velocity.
KeployeBPF-basedKeploy uses eBPF to record real API calls and responses from your running application, then replays them as regression tests. It auto-generates mocks for downstream dependencies and handles non-deterministic fields like timestamps through time-freezing. You get a complete regression suite plus dependency mocks without writing any code.
Hoverfly runs as a lightweight HTTP/HTTPS proxy written in Go. In Capture Mode it records real request/response pairs between your app and external services, and in Simulate Mode it replays those responses so tests never hit the real dependency. Simulations are stored as JSON that teams can export, edit, and share, with options to inject latency, failures, or rate limits.
When to use each tool
Specific scenarios where each tool delivers the most value.
Keploy is the better fit when…
- Want to auto-generate a full regression test suite, not just simulate dependencies
- Need mocks for databases and internal services, not only external HTTP APIs
- Prefer eBPF capture with no proxy configuration or certificate management
- Need automatic handling of non-deterministic fields like timestamps and UUIDs
- Want testing to work across many languages and protocols beyond HTTP
Hoverfly is the better fit when…
- Primary goal is virtualizing slow or flaky third-party HTTP APIs in tests
- Want a lightweight standalone proxy you can drop into any test environment
- Need to simulate network latency, failures, and rate limits for edge-case testing
- Prefer editable, exportable JSON simulations you can hand-craft and share
- Your team already runs Java tests and wants native Hoverfly bindings
Compare the full workflow for your own stack.
The workflow you're escaping
Same starting point, same finish line. One path is short because Keploy does the tedious middle for you — the other is where teams lose days every sprint.
Without Keploy (Hoverfly / manual)
Every dependency is your problem, and every code change ripples back through the test suite you hand-built.
With Keploy
Record once from real traffic, replay anywhere. Tests and mocks are generated and stay in sync automatically.
Cut the maintenance middle out of your test suite.
The test maintenance trap
With Hoverfly, every feature commit generates a hidden tax — a follow-up "fix tests" commit. The commit history tells the whole story.
Deterministic replays, no flaky tests — see how.
Switch from Hoverfly in minutes
Choose the path that fits your workflow. Both are up and running the same day.
Install, record real API traffic, then replay it as regression tests — zero code changes, zero framework dependencies.
# 1. Installcurl --silent -O https://keploy.io/install.sh && source install.sh# 2. Record your traffickeploy record -c "your-start-command"# 3. Replay as testskeploy test -c "your-start-command" --delay 10Paste your cURLs, drop in an OpenAPI spec or Postman collection, and click Generate. Keploy builds your test suite in seconds.
Real-world scenarios
How Keploy handles the challenges your team actually faces.
Your app depends on a slow, rate-limited third-party payment API
Keploy captures the real calls to the payment API alongside your app's traffic and auto-generates both tests and a mock of that dependency. Tests replay against the mock, so CI never hits the real API or burns rate limits.
Hoverfly is purpose-built for this — run it in capture mode once against the payment API, then switch to simulate mode so every test run replays the recorded responses without touching the real service.
You need a regression suite for an existing service, not just dependency stubs
Keploy records inbound traffic to your service and turns each request/response into a replayable test case, automatically stubbing downstream calls. You get graded coverage of your own endpoints out of the box.
Hoverfly simulates the external services your app calls but does not generate test cases for your own endpoints. You still need a separate test framework to assert your service's behavior.
Join the teams shipping with confidence on Keploy.
What you write vs what Keploy writes
The same test coverage — one approach takes hours of setup and ongoing maintenance, the other takes five minutes and zero boilerplate.
Every new endpoint needs a new file. Every refactor breaks tests. Every non-deterministic value (timestamps, IDs) needs custom handling.
Keploy captures the real request, response, and all dependency calls. Non-deterministic fields are auto-detected and excluded from assertions.
Frequently asked questions
Common questions about choosing between Keploy and Hoverfly.
Still have questions? The docs and community can help.
Looking for a Hoverfly alternative?
Engineering teams evaluating Hoverfly alternatives often compare it with Keploy for API testing and regression coverage. Keploy captures real production traffic via eBPF and auto-generates tests with dependency mocks — requiring zero code changes. The key differences come down to how tests are generated (traffic-based vs manual), how dependencies are mocked (automatic vs configured), and what infrastructure changes are needed (none vs SDK/sidecar/containers).
Ready to stop writing tests manually?
Keploy captures your real API traffic and turns it into a regression suite automatically. Zero code changes. Full coverage from day one.