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Best API Design Tools in 2026

Planning an API means defining its contract and checking how changes fit the development workflow. Compared on AsyncAPI support, contract validation, free plan, Git synchronization, included team seats, mock server, OpenAPI support, paid from, and team collaboration, these tools offer useful dimensions for weighing specification and coordination needs. Apidog, Microcks, and Apollo Studio are among the available options. Consider which specifications your work relies on, whether contract validation and mock servers fit your process, and how Git synchronization or collaboration may support a team. Free-plan availability, included seats, and paid-from pricing add practical details to compare.

  1. 1

    Apidog

    Free plan APIExtensionLinux+4

    Apidog combines API design, testing, mocking, and documentation with specification-driven workflows and deployment choices. Check the plan details and database limits against your team's requirements.

    7.7 Free plan · paid from $9/user/mo (annual) · 14-day trial Visit site
  2. 2

    Apollo Studio

    Free plan APIExtensionLinux+4

    Apollo Studio brings GraphQL schema management, operation exploration, review controls, and observability into one interface.

    7.7 Free plan · paid from $5 Visit site
  3. 3

    Microcks

    Free plan APIExtensionLinux+4

    Microcks combines API mocking, contract testing, and pipeline automation in an open-source tool.

    7.5 Free plan Visit site
  4. 4

    Mockoon

    Free plan APILinuxMac+3

    Mockoon covers local mock creation as well as automated, serverless, and private deployment workflows.

    7.5 Free plan · paid from $100/mo (annual) Visit site
  5. 5

    MockServer

    Free plan APILinuxMac+3

    MockServer covers mocking, proxying, verification, and chaos testing across a broad set of protocols and deployment options.

    7.5 Free plan Visit site
  6. 6

    GraphQL Hive

    Free plan APISelf-hostedWeb

    GraphQL Hive combines schema management, API observability, and gateway capabilities, with a free plan for small projects.

    7.4 Open source Visit site
  7. 7

    oasdiff

    Free plan APILinuxMac+3

    oasdiff offers specification comparisons through a CLI, GitHub Action, and browser tool, with review options for teams.

    7.4 Free plan · paid from $100/mo · 30-day trial Visit site
  8. 8

    Assertible

    Free plan APIWeb

    Choose Assertible if you need HTTP service checks, deployment smoke tests, or API test synchronization with common specification formats and Postman collections.

    7.3 Free plan · paid from $25/mo Visit site
  9. 9

    AsyncAPI Studio

    Free plan ExtensionLinuxMac+3

    AsyncAPI Studio brings document editing, validation, previews, and event-flow visualization together, with options for browser or self-hosted use.

    7.3 Open source Visit site
  10. 10

    Pact

    Free plan APILinuxMac+2

    Pact focuses on contract-based integration checks, with tools for HTTP, messaging and deployment compatibility workflows.

    7.3 Free plan Visit site
  11. 11

    PactFlow

    Free plan APILinuxSelf-hosted+1

    Pick PactFlow if your team needs a managed broker for Pact or OpenAPI contract testing, especially when you want pull request checks and automation options.

    7.3 Free plan · paid from $115.42/mo (annual) · 14-day trial Visit site
  12. 12

    Postman

    by Postman
    Free plan ExtensionLinuxMac+2

    Postman combines API creation, testing, documentation, and monitoring in one platform, with a free plan and paid options. Check plan availability and the annual billing terms before choosing a tier.

    7.3 Free plan · paid from $9/mo (annual) Visit site
  13. 13

    Schemathesis

    Free plan LinuxMacSelf-hosted+1

    Schemathesis provides schema-based API testing with adaptive and stateful workflows, authentication options, and CI/CD integrations.

    7.2 Free plan Visit site
  14. 14

    OpenAPI Studio

    Free plan Self-hostedWeb

    Choose OpenAPI Studio if you want a visual API editor with request recipes, MCP tools, and support for both OpenAPI and AsyncAPI.

    7.1 Free plan · paid from $9/mo Visit site
  15. 15

    Redocly

    by Redocly
    Free plan APIExtensionWeb

    Redocly brings API references, collaboration, governance, and monitoring into one product set, with an open-source CLI and VS Code extension.

    7.1 From $10/user/mo · 30-day trial Visit site
  16. 16

    TypeSpec

    Free plan ExtensionLinuxMac+2

    TypeSpec combines API modeling with generation of several common schema and specification formats.

    7.0 Open source Visit site
  17. 17

    Stoplight Prism

    Free plan APISelf-hostedWeb

    Choose Prism if you need a free, open-source server for mocking APIs, validating data, or checking a target API against its OpenAPI document.

    6.9 Free plan Visit site
  18. 18

    WireMock

    Free plan APILinuxMac+3

    WireMock Cloud supports a broad set of protocols and workflows, with local and CI/CD simulation options. Check the Free plan's call cap and the Enterprise quote-based pricing against your needs.

    6.9 Free plan Visit site
  19. 19

    Stoplight Elements

    Free plan Self-hostedWeb

    Stoplight Elements covers core interactive API documentation needs with OpenAPI support, code examples, and an embedded console.

    6.8 Free plan Visit site
  20. 20

    Swagger Editor

    Free plan Self-hostedWeb

    Choose Swagger Editor for a free way to write and validate API definitions across Swagger, OpenAPI, and AsyncAPI formats.

    6.8 Free plan Visit site
  21. 21

    Smithy

    Free plan LinuxMacWindows

    Smithy provides a shared API model with validation and generation for clients, servers, and documentation.

    6.7 Open source Visit site
  22. 22

    SwaggerHub

    by SwaggerHub
    Free plan Self-hostedWeb

    SwaggerHub brings API design, documentation, testing, and governance into a set of team tools.

    6.7 Pricing on request Visit site
  23. 23

    vacuum

    Free plan APIExtensionLinux+3

    Choose vacuum if you need a free, open-source linter with CLI, library, editor and CI options for supported API specifications.

    6.7 Open source Visit site
  24. 24

    Spectral

    Free plan LinuxMacWindows
    6.0 Free plan Visit site
  25. 25

    WSO2 API Designer

    Free trial ExtensionLinuxMac+2

    WSO2 API Designer adds visual editing, governance rules, and optional AI assistance to OpenAPI work in VS Code.

    5.8 Open source · 30-day trial Visit site

#1Places #1, #2, #3, #4, #5 on this list can be bought by the makers of the software on it. See the price

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