Top Free API Development Tools - Page 3

How Many API Development Tools Products Does G2 Track?

Total Products under this Category: 71

Category Stats (Sep 2026)

  • Average Rating: 4.5/5 (↓0.01 vs Aug 2026) The average rating of products in this category, based on all submitted ratings
  • Top Trending Product: Kong Konnect (+0.09%) - Among all products in this category, Kong Konnect recorded the largest rating increase compared to last month

Last updated: September 15, 2026

How Does G2 Rank API Development Tools Products?

Why You Can Trust G2's Software Rankings:

  • 30 Analysts and Data Experts
  • 7,400+ Authentic Reviews
  • 71+ Products
  • Unbiased Rankings

G2's software rankings are built on verified user reviews, rigorous moderation, and a consistent research methodology maintained by a team of analysts and data experts. Each product is measured using the same transparent criteria, with no paid placement or vendor influence. While reviews reflect real user experiences, which can be subjective, they offer valuable insight into how software performs in the hands of professionals. Together, these inputs power the G2 Score, a standardized way to compare tools within every category.

G2 Grid® for API Development Tools

G2 Grid® for API Development Tools plotting products by satisfaction and market presence

Highlighted products: Postman, MuleSoft Anypoint Platform, Apidog, Workato, Apify, Boomi, IBM API Connect, and Kong Konnect.

Underlying data: [Grid® JSON](https://www.g2.com/categories/api-development/grids.json?focus%5B%5D=postman&focus%5B%5D=mulesoft-anypoint-platform&focus%5B%5D=apidog&focus%5B%5D=workato&focus%5B%5D=apify&focus%5B%5D=boomi&focus%5B%5D=ibm-api-connect&focus%5B%5D=kong-inc-kong-konnect)

Apister

Apister is a no-code API builder and API hosting platform that helps teams and individuals design, build, deploy, and manage APIs without writing traditional code. Through a visual API flow editor, users can create complex API logic using branching, loops, database operations, and AI-powered actions — all with intuitive drag-and-drop tools. Apister supports multiple databases, including PostgreSQL, MySQL, and MongoDB, and includes built-in query builders and workflow automation features. These capabilities allow product teams, startups, and non-developers to rapidly create scalable backend APIs and maintain them efficiently. Apister also integrates with leading AI services such as OpenAI and Anthropic Claude, enabling intelligent decision-making and AI-driven workflows within APIs. Designed for building backend services, internal tools, and public APIs, Apister streamlines API development and management by removing traditional coding complexity, helping teams accelerate delivery and focus on building functional, reliable solutions.

Who Is the Company Behind Apister?

  • Seller: Apister
  • Year Founded: 2025
  • HQ Location: N/A
  • LinkedIn® Page: linkedin.com
    6 employees on LinkedIn®

AutoStub 2.0

AutoStub™ is an essential tool to fasten API development. It can significantly reduce your build time by quickly designing, prototyping, documenting and testing the APIs. AutoStub creates a functional mock that allows developers or prospective users to work with the API before it’s fully implemented. It allows developers to mock web services, helping developers of applications that depend on APIs to speed development and improve quality by facilitating functional testing. Key Features: 1. Simulate ReST and SOAP services 2. Input format - Swagger files for ReST, WSDL files for SOAP services 3. Support for GET, POST, PUT, DELETE methods in ReST 4. Create WSDL/Swagger 2.0 based mock services; generate dummy data for API testing 5. Get an endpoint URL that can be used on a third party SOAP client tool 6. Improves quality by facilitating functional testing 7. Can handle multiple test scenarios together

Who Is the Company Behind AutoStub 2.0?

EverREST

EverRest is a Salesforce partner and on-demand talent network specializing in assembling expert-led Salesforce teams for businesses of all sizes. Their offerings include team augmentation with pre-vetted Salesforce developers, architects, and admins, as well as fully managed delivery teams custom-built for specific projects. With a focus on speed, quality, and flexibility, EverRest enables companies to launch and scale Salesforce implementations in days, without the delays of traditional hiring. For more information, visit their website at everrest.org.

Who Is the Company Behind EverREST?

  • Seller: EverREST
  • Year Founded: 2022
  • HQ Location: Kraków, PL
  • LinkedIn® Page: www.linkedin.com
    15 employees on LinkedIn®

Kreya

Kreya is a privacy-first desktop client that helps your team explore, test, and automate API workflows from one place without SaaS lock-in or messy tooling sprawl. Kreya supports - gRPC - REST - WebSocket - Server-Sent Events - GraphQL (coming soon) - SOAP (coming soon) All project data is stored locally and is explicitely designed to be synced via git (or any other VCS), giving you full control. Privacy-first architecture keeps all data on your device. Work fully offline without Kreya contacting any external server. Write tests, ranging from simple to advanced use cases, to catch regressions and other bugs. Use snapshot testing to automatically highlight unintentional changes before publishing them to production. Kreya includes a CLI with unlimited runs, allowing you to continously test your APIs. Support for popular platforms such as GitHub Actions, GitLab CI/CD or Docker image is also included. Inspect streaming, unary, and multi-channel traffic with built-in HTTP/1.1, HTTP/2 and HTTP/3 support. View messages immediately after they arrive and test APIs in real time. Inspect detailed timing information to find bottlenecks. Kreya introduces an innovative, reusable auth vault with support for most authentications mechanisms: - OAuth 2 / OpenID Connect - Basic auth - JWT - Windows authentication (NTLM/Kerberos) - AWS signature v4 - API keys - Mutual TLS (mTLS) Explore further powerful features: - Mock data generation - Import APIs from OpenAPI documents, gRPC server reflection or Postman - Use environments and templating - Request history - Custom proxy configuration - Windows named pipe - Local Unix domain sockets

Who Is the Company Behind Kreya?

Sparrow

Sparrow is an AI-powered API testing platform designed to streamline and automate testing for developers, QA engineers, and DevOps teams. It supports REST and GraphQL APIs, integrates seamlessly with Git for version control, and offers self-hosting for secure infrastructure management. Key features include AI-driven test automation, real-time collaboration, mock servers, automated data generation, and environment vaults. With new enhancements like active sync with Swagger/OpenAPI, AI-powered test flow completion, and improved team collaboration, Sparrow helps teams test faster, reduce manual errors, and scale efficiently—making API testing seamless, intelligent, and collaborative.

Who Is the Company Behind Sparrow?

  • Seller: Techdome
  • Year Founded: 2020
  • HQ Location: Hyderabad, IN
  • LinkedIn® Page: www.linkedin.com
    107 employees on LinkedIn®
  • Ownership: Rahul Joshi
  • Phone: 7723849516

Yaak

Yaak is a fast, offline-first API client that gets out of your way. No accounts, no sync, no telemetry. Store your API requests locally, end-to-end encrypted, and versioned with Git. - Local-First by Default → Data never leaves your machine. No login, no cloud sync. - Git-Native Workflow → Store requests as files, commit changes, and collaborate using Git. - Agent-Friendly CLI → Let AI tools like Claude or Codex create and run requests directly. - Extensible Plugin System → Add authentication, templating, and custom workflows with plugins. - Fast & Lightweight → Built with Rust and React for a responsive, multi-window workflow.

Who Is the Company Behind Yaak?

Adam Crivello
AC
Researched and written by Adam Crivello
Updated November 18, 2024