What MockServer Can’t Test, Keploy Cancatch what breaks
Auto-Generated Tests from Traffic vs Expectation-Based HTTP Mocking
Keploy uses eBPF to capture real production traffic and auto-generate regression tests plus dependency mocks with zero code changes. MockServer is an open-source HTTP(S) mock and proxy where you define expectations — request matchers paired with responses — to mock APIs, inspect traffic, and inject failures across HTTP, gRPC, WebSockets, and more. Keploy focuses on generating a full test suite from real behavior; MockServer focuses on precise, expectation-based control of mocked and proxied traffic.
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 MockServer
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 suite, not just define expectations
Prefer eBPF capture over hand-writing request matchers and responses
Need automatic handling of non-deterministic fields like timestamps and UUIDs
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 expectation-based mocks only
Zero code changes — captures via eBPF at kernel level
No app code changes, but expectations are configured by hand or in test code
Auto-generates mocks for all downstream dependencies
Manually defined expectations, or recorded via proxy mode
Matches replayed traffic against recorded request/response pairs
Rich matchers: method, path, headers, query, body via regex/XPath/JSON Schema
Built-in time-freezing and field normalization
Velocity/Mustache response templating for dynamic values
HTTP, gRPC, and many DB/queue protocols captured at network level
HTTP/1.1, HTTP/2, gRPC, WebSockets, TCP on a single port
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 with no expectation setup.
MockServer runs as a mock server and proxy on a single port. You define expectations — a request matcher (method, path, headers, query, cookies, body via exact, regex, XPath, or JSON Schema) plus the response to return. It can proxy real traffic to inspect and modify it, record traffic to build expectations, template responses with Velocity or Mustache, verify requests, and inject latency or failures. Clients exist for Java, Node, Python, Ruby, Go, and more.
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 suite, not just define expectations
- Prefer eBPF capture over hand-writing request matchers and responses
- Need automatic handling of non-deterministic fields like timestamps and UUIDs
- Want mocks generated from real traffic instead of manually authored expectations
- Prefer a low-config workflow: install agent, run app, tests appear
MockServer is the better fit when…
- Need precise, expectation-based request matching with regex, XPath, or JSON Schema
- Want a single tool that both mocks and proxies traffic on one port
- Need to verify requests were sent a specific number of times or in a set order
- Require multi-protocol mocking across HTTP/2, gRPC, WebSockets, and TCP
- Prefer native mock clients embedded in Java, Node, Python, or Ruby tests
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 (MockServer / 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 MockServer, 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 MockServer 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.
You want a regression suite for your own service without writing mocks
Keploy records inbound traffic and auto-generates replayable regression tests, stubbing downstream calls automatically. You get coverage of your endpoints with no expectations to author.
MockServer stands in for dependencies your service calls, but does not generate test cases for your service. You still write the tests and define each expectation by hand or record them via proxy.
You need to verify a dependency was called a specific number of times
Keploy replays captured traffic to check your service's responses match recorded behavior; call-count verification of dependencies is not its primary focus.
MockServer excels here — it can verify that a matching request was received a specific number of times, or that a sequence of requests arrived in a particular order.
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 MockServer.
Still have questions? The docs and community can help.
Looking for a MockServer alternative?
Engineering teams evaluating MockServer 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.