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Best API Development Tools in 2026

Use API development tools to design, test, mock, document, and otherwise work with APIs. This list is for people choosing a tool on a budget, including teams that need web, desktop, API, or self-hosted options.

  1. 1

    Bruno

    Free plan Open source APIExtensionLinux+3

    Bruno pairs API testing and automation with Git-friendly plain-text collections and companion tools.

    9.2 Free plan · paid from $6/user/mo (annual) · 14-day trial Visit site
  2. 2

    HTTPie

    Free plan Open source LinuxMacWeb+1

    HTTPie offers command-line API testing alongside a graphical app for desktop and web. The CLI plan is open-source, while the Desktop and Web plan is in public beta; both are listed as free.

    9.2 Free plan Visit site
  3. 3

    Scalar

    Free plan Open source APILinuxMac+3

    Scalar brings several API documentation and management tools together, with hosted and self-hosted options.

    8.8 Free plan · paid from $150/mo Visit site
  4. 4

    SoapUI

    Free plan Open source APILinuxMac+2

    SoapUI Open Source offers API testing, mocking, and command-line automation across major listed protocols.

    8.8 Free plan Visit site
  5. 5

    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
  6. 6

    Beeceptor

    Free plan APILinuxMac+3

    Beeceptor combines configurable mocks with proxying, traffic recording, and failure simulation across a wide range of API protocols.

    7.6 Free plan · paid from $10/mo · 10-day trial Visit site
  7. 7

    HTTP Toolkit

    Free plan AndroidiPhoneLinux+3

    HTTP Toolkit offers a free starting point for traffic inspection and manual breakpoints, with automation and reusable rules in Professional.

    7.5 Free plan Visit site
  8. 8

    Hurl

    Free plan LinuxMacSelf-hosted+1

    Hurl combines request workflows, response assertions, and CI reporting in a free command-line tool. Check the listed Linux and Windows requirements before choosing an installation option.

    7.5 Free plan Visit site
  9. 9

    Insomnia

    Free plan LinuxMacSelf-hosted+1

    Insomnia covers API design and client workflows alongside mocking, CI/CD execution, and team collaboration.

    7.5 Free plan · paid from $12/user/mo · 14-day trial Visit site
  10. 10

    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.

    7.4 Free plan · paid from $25/mo Visit site
  11. 11

    Mockoon

    Free plan APILinuxMac+3

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

    7.4 Free plan · paid from $100/mo (annual) Visit site
  12. 12

    OpenAPI Generator

    Free plan LinuxMacSelf-hosted+2

    OpenAPI Generator covers client, server-stub, and documentation generation, with options to customize output and integrate with common build workflows.

    7.4 Free plan Visit site
  13. 13

    Pact

    Free plan APILinuxMac+2

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

    7.4 Free plan Visit site
  14. 14

    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.

    7.4 Free plan · paid from $9/mo (annual) Visit site
  15. 15

    Kreya

    by Kreya
    Free plan LinuxMacWindows

    Kreya combines broad protocol support with scripted and snapshot testing, imports, and CI/CD use.

    7.3 Free plan · paid from $5/user/mo · 10-day trial Visit site
  16. 16

    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
  17. 17

    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
  18. 18

    Speakeasy

    Free plan APILinuxMac+2

    Speakeasy brings MCP governance, workflow assistants, and API tooling into one platform. Teams evaluating the Enterprise plan will need to request pricing.

    7.1 Free plan · pricing on request · 14-day trial Visit site
  19. 19

    Stainless

    Free plan LinuxMacWeb

    Stainless brings SDK generation, API documentation, and code-mode MCP servers together around OpenAPI.

    7.0 Free plan · 30-day trial Visit site
  20. 20

    Testfully

    by Testfully
    Free plan ExtensionLinuxMac+2

    Testfully combines API testing, monitoring, and team collaboration across cloud and offline workspaces.

    7.0 Free plan · paid from $14/user/mo (annual) · 14-day trial Visit site
  21. 21

    Thunder Client

    by Thunder Client
    Free plan ExtensionLinuxMac+1

    Choose Thunder Client if you want an API client inside your IDE, with local data storage and graphical response validation.

    7.0 Free plan · paid from $3/user/mo (annual) · 14-day trial Visit site
  22. 22

    ReadMe

    by ReadMe
    Free plan Web
    6.9 Free plan · paid from $250/mo (annual) · 14-day trial Visit site
  23. 23

    WireMock

    Free plan APILinuxSelf-hosted+1

    WireMock offers request matching, response simulation, and replay for testing against simulated dependencies.

    6.9 Free plan Visit site
  24. 24

    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
  25. 25

    Yaak

    Free plan LinuxMacWindows

    Yaak brings API requests and Git-oriented organization together in a desktop client with local data storage.

    6.8 Free plan · paid from $79/user/yr · 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

Compare free plans, trial periods, and the paid starting price. Review API design and testing capabilities, mock-server support, specification formats, deployment choices, version-control features, available platforms, and licensing when code access matters.

Questions

Are free API development tools available?

Yes. Listed tools include free and freemium options with free plans.

Do these tools offer free trials?

Yes. Listed trials run for 10 or 14 days. Check the specific tool's pricing terms.

What paid starting prices are listed?

Where a paid price is stated, starts range from $6/user/mo (annual) to $100/mo (annual). Other entries show different pricing notes.

Which platforms can these tools run on?

The list covers Linux, macOS, Windows, web, self-hosted environments, and API access.

Can I use open-source API tools?

Yes. Some entries provide open-source code. Review the licence before using or modifying it.

What should I compare between API tools?

Evaluate free-plan availability, paid starting prices, API design and testing, mock servers, specification formats, deployment, and version control.

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