Mockoon provides a desktop editor, a headless CLI, and proxy recording that can create routes automatically. Gostly brings recorded API behavior into a self-hosted platform with controls for state, failures, and virtual time. Start with your existing HAR, Postman, or OpenAPI files, then record the behavior your tests need.
Recording and deployment details checked September 5, 2026 against Mockoon’s recording documentation and desktop and CLI downloads.
Mockoon supports authoring and importing mocks, recording proxied requests, and running those mocks through its desktop application or CLI. Its recording mode creates routes from HTTP transactions, including headers and bodies.
The comparison is about workflow: evaluate how each tool handles your recorded behavior, shared state, failure scenarios, and CI setup. Recording by itself is useful in both; choose the controls that match the environment your team needs to reproduce.
Gostly is built for that case. You put its Rust proxy in front of your upstream and run the self-hosted stack in your perimeter (Docker Compose); in LEARN mode it captures the exchanges your tests exercise, then replays the recorded traffic locally in MOCK mode — including HTTPS. Your recorded traffic stays on your own infrastructure; sensitive headers are redacted before anything is written to disk. Recorded matches do not require model inference; AI is an opt-in gap-fill, grounded by your recordings rather than a free-text prompt.
And because it runs as your own single-tenant deployment, the controls a security review asks for are built in: SSO via SAML or OIDC, role-based access control, and an administrative audit log on Team. Your recorded traffic never leaves your perimeter — each deployment is single-tenant, with application tenant scoping and database policies as an additional layer.
Faker generates a name that looks real. Gostly returns the name the API actually sent. A Mockoon fixture is only ever as right as what you remembered to type; Gostly’s mock is the recording — replayed from your library, inside your own perimeter.
take the upstream offline — the recorded library still serves, 0 live calls
| Feature | Mockoon | Gostly |
|---|---|---|
| Free, OSS desktop GUI | MIT | No |
| Free OSS proxy / server | Headless CLI | Licensed platform; separate proxy source distribution |
| Mock source | GUI authoring, proxy recording, and imports | Recorded from real traffic |
| Records real upstream traffic | Proxy recording creates routes from requests and responses | Records upstream behavior for local replay |
| Serves mocks over TLS | Yes | Yes |
| Library on day one (no recordings yet) | OpenAPI import and reusable mocks | Seed from a HAR / Postman / OpenAPI file — full library before you record |
| AI-assisted endpoint generation | from a text prompt | opt-in gap-fill grounded by your recordings |
| Recorded matches without LLM inference | Yes | Yes |
| CLI for CI | Yes | Yes |
| Team workspace + multi-seat sync | Cloud Team | Team plan |
| Latency / status-code injection | Yes | Yes |
| Chaos / failure injection | manual responses | Markov chaos that learns a degradation profile from your traffic |
| Stateful CRUD across requests | CRUD routes and persistent data buckets | shipping (statechart) |
| Live drift detection vs the real upstream | OpenAPI import and request recording; compare your drift workflow | Re-record + compare — emits drift events + a freshness score |
| Outbound TLS the upstream accepts | No | JA4-accurate browser-fingerprint impersonation (Pro+) |
| SSO, RBAC, audit log | Cloud account controls (paid) | SAML + OIDC SSO, RBAC, administrative audit log on Team |
| Self-hostable | Desktop or headless CLI | Self-hosted platform (Docker Compose) |
Statecharts and drift detection ship today. AI gap-fill on Gostly is opt-in and grounded by your recordings, not a free-text prompt. gRPC and broader async-protocol capture are on the roadmap.
Choose Mockoon when
Choose Gostly when
| Tier | Mockoon | Gostly |
|---|---|---|
| Free | Desktop app, MIT, unlimited | 14-day Pro trial · no credit card required |
| Solo / Pro | $10 / mo (Mockoon Solo) | $10 / mo single user (unlimited services, AI on miss) |
| Team | $100 / mo for 5 seats (Mockoon Team) | $79 / seat / mo (min 3 seats) |
| Enterprise | Mockoon Enterprise — custom | Custom pricing |
At the Pro tier the prices are identical; the products are not. At the Team tier Gostly is $79/seat/mo versus Mockoon’s $100 for five seats — so for very small teams Gostly tracks lower, and for larger teams Mockoon’s flat block-of-five may be cheaper. The right comparison is workflow, not sticker price: the moment your constraint becomes “the mock has to match what the real API actually returned,” recording stops being a feature and starts being the requirement.
The objection that kills most Mockoon switches is “I have no recordings yet, so I’d be starting from a blank canvas.” You aren’t. Drop a HAR capture, a Postman collection, or an OpenAPI spec into the dashboard and Gostly seeds a working mock library before you proxy a single request — the same library your recorded traffic lands in. Then real traffic sharpens it to ground truth. A hand-authored fixture is only ever as right as what you remembered to type.
In the dashboard, open Cold-start seeding, drag in the HAR / Postman / OpenAPI file, pick the service, and commit. The mocks land in the same library your recorded traffic does — flip the proxy to MOCK and they serve immediately. Then run your real test suite through the containerized proxy in LEARN mode to sharpen the library to ground truth.
Self-hosted, recorded from real traffic, deterministic in CI. Run it against your staging upstream for an hour and see whether it produces a mock you trust.
Evaluating for a team of 3+? We’d love to talk before you commit.