Tools / Best tools / API mocking
CheckOps
Best API mocking tools in 2026
These are API mocking and service-virtualization tools in the CheckOps directory. The directory has 55 tagged entries in this area; this page lists 15.
How we picked
CheckOps is a genuine and free directory. There are no paid sponsors, featured listings, or paid placement on these pages. The shortlist is built from tools already in the directory whose tags match the topic, with a preference for entries that have a fuller CheckOps page so the facts in the table can be checked against the source essay. This is not a claim that one tool is objectively better than another, and it is not a paid ranking.
Well-known tools that already have a CheckOps page in this area are listed first. The rest of the shortlist is filled from other tagged entries, preferring fuller essays so the facts in the table can be checked. That order is a way to keep the page useful, not a quality score and not a paid ranking.
Tools
W
M2. Mockoon
Mockoon is the easiest and quickest way to run mock APIs locally.
Read the CheckOps page · Open source
M3. Mock Service Worker (MSW)
Mock Service Worker (MSW) is an MIT-licensed API mocking library that intercepts network requests at the network level in browsers (via a Service Worker) and Node.js, for REST, GraphQL and WebSocket APIs.
Read the CheckOps page · Open source
M4. Moto
Moto is an Apache-2.0 Python library that mocks AWS services in tests, with decorators for boto3 code and a standalone server mode for other languages.
Read the CheckOps page · Open source
M5. mountebank
mountebank is an MIT-licensed, open-source service virtualization tool that creates multi-protocol test doubles (imposters) over HTTP, HTTPS, TCP and SMTP, configured through a REST API, with proxy recording and JavaScript injection.
Read the CheckOps page · Open source
S6. Specmatic
Specmatic is an MIT-licensed contract-driven development tool that turns API specifications (such as OpenAPI) into executable contracts for contract tests, intelligent service virtualization and backward-compatibility checks.
Read the CheckOps page · Open source
S7. Smocker
Smocker is an MIT-licensed HTTP mock server written in Go with a web UI, YAML or JSON mock definitions, and request history for checking what your service called.
Read the CheckOps page · Open source
T8. Telerek TestStudio
API testing with Test Studio helps you enhance your end-to-end testing strategy to cover test scenarios that require API calls.
Read the CheckOps page · Commercial, with a free or trial tier tagged
- B
9. Beeceptor
Create AI-powered mock servers in seconds.
Read the CheckOps page · Commercial, with a free or trial tier tagged
H10. Hoverfly
Lightweight service virtualization/ API simulation / API mocking tool for developers and testers.
Read the CheckOps page · Open source
- D
11. DeepFake HTTP
DeepfakeHTTP is a web server that uses HTTP dumps as a source for responses. This tool allows you to test clients against REST, GraphQL, and other APIs.
Read the CheckOps page · Open source
M12. MockLab
Platform for creating, testing, and sharing HTTP mock servers.
Read the CheckOps page · Commercial, with a free or trial tier tagged
R
R14. RoboHydra HTTP
RoboHydra Server is a great API testing solution for those who don’t have access to a server but need to test something.
Read the CheckOps page · Open source
S15. Stoplight Prism
Accelerate API development with realistic mock servers powered by API descriptions.
Read the CheckOps page · Open source
Comparison
License, pricing model, and languages or platforms are taken from tags on each CheckOps page. Pricing notes are a short excerpt from that page's Pricing section when one exists. A blank or "not stated" cell means the CheckOps page does not record it.
| Tool | License | Pricing model | Languages / platforms | Pricing notes |
|---|---|---|---|---|
| WireMock | Open source | Free, Open source | Not stated in the tags on the CheckOps page | Wiremock is open-source software, making it free to use under the Apache 2.0 license. |
| Mockoon | Open source | Free, Open source | Not stated in the tags on the CheckOps page | Mockoon is available for free as an open-source tool, which makes it highly accessible for individuals and teams looking to mock APIs without incurring costs. |
| Mock Service Worker (MSW) | Open source | Free, Open source | Javascript | Mock Service Worker (MSW) is free and open source under the MIT licence. |
| Moto | Open source | Free, Open source | Python | Moto is free and open source under the Apache-2.0 licence. |
| mountebank | Open source | Free, Open source | Javascript | mountebank is free and open source under the MIT licence. |
| Specmatic | Open source | Free, Open source | Java | Specmatic is free and open source under the MIT licence. |
| Smocker | Open source | Free, Open source | Golang, Docker | Smocker is free and open source under the MIT licence. |
| Telerek TestStudio | Commercial, with a free or trial tier tagged | Paid, Trial | Not stated in the tags on the CheckOps page | Not stated in a Pricing section. |
| Beeceptor | Commercial, with a free or trial tier tagged | Free, Free tier, Paid, Trial | Not stated in the tags on the CheckOps page | Beeceptor offers a flexible pricing structure to cater to different user needs: Free Plan: The free plan includes 50 requests/day and 3 rules per endpoint. |
| Hoverfly | Open source | Free, Open source | Not stated in the tags on the CheckOps page | Not stated in a Pricing section. |
| DeepFake HTTP | Open source | Free, Open source | Not stated in the tags on the CheckOps page | DeepFakeHTTP is an open-source tool, available for free under the MIT license. This makes it accessible to developers and organizations of all sizes, without any licensing fees or subscription costs. |
| MockLab | Commercial, with a free or trial tier tagged | Free tier, Paid | Not stated in the tags on the CheckOps page | MockLab offers a range of pricing tiers to accommodate different usage needs. The free tier includes basic features with limitations on the number of mock endpoints and requests per month. |
| RestQA | Open source | Free, Open source | Polygot | RestQA is completely free and open-source, which makes it highly accessible for teams and individual developers. |
| RoboHydra HTTP | Open source | Free, Open source | Not stated in the tags on the CheckOps page | As an open-source tool, RoboHydra is available for free. There are no licensing fees or premium versions, making it a cost-effective solution for teams or individuals looking for a flexible, customizable API testing… |
| Stoplight Prism | Open source | Free, Open source | Not stated in the tags on the CheckOps page | Stoplight Prism operates under a freemium model, offering a free version with essential features and premium plans for organizations seeking more advanced capabilities. |
FAQ
- How did CheckOps pick these tools?
- CheckOps is a genuine and free directory. There are no paid sponsors, featured listings, or paid placement on these pages. The shortlist is built from tools already in the directory whose tags match the topic, with a preference for entries that have a fuller CheckOps page so the facts in the table can be checked against the source essay. This is not a claim that one tool is objectively better than another, and it is not a paid ranking.
- Does CheckOps sell placement on this list?
- No. CheckOps does not sell featured or paid placement, and this page does not include sponsored listings.
- How many api mocking tools are in the directory?
- This shortlist has 15 tools. The directory has 55 tagged entries in this area. See the Integration testing stage for the wider set.
- Are the one-line summaries complete reviews?
- No. Each line is taken from the tool's CheckOps page (the short description, or the opening of the essay when that description is empty). Open the linked page for the full write-up.