Apps similar to Insomnia REST Client include Bruno, which is open source with a free version. Other options are Postman, Yaak, HTTP Toolkit and Hoppscotch. You're spoiled for choice with API Clients like Insomnia REST Client: we list more than 100 alternatives for Windows, Mac, Linux, the web and self-hosting.
Slingshot is a web-based HTTP request client that is highly performant, low on resources, privacy respecting, local-first, free and open-source. It stores all your data locally in your browser. It allows you to import and export OpenAPI specs and Postman collections.
Sweden
EU
APIBuilderHQ is a zero-friction alternative to heavy API clients like Postman. Built entirely for the browser — no desktop app, no mandatory accounts, no cloud sync. Your collections and request data stay in localStorage on your device.
United States
A fast, lightweight REST API client for developers. Test, debug, and organize your APIs locally without cloud sync. Free
United States
APISpider is a lightweight API client for testing, debugging, and documenting REST APIs. It includes request history, collections, environment variables, mock servers, and API docs — all designed to keep your workflow fast and distraction-free.
ReqResp is a fast, lightweight, and modern API testing app designed for developers, testers, and backend engineers. It helps you create, send, and analyze HTTP requests with ease — anytime, anywhere.
Vietnam
Create multi-step HTTP API checks in a visual editor by chaining requests, extracting response values, applying conditional logic, and setting assertions. Runs can be scheduled or triggered in CI/CD, logging payloads, assertion results, and timings for debugging.
SpainEU
Resonance is a local-first, zero-account API client application designed to provide an excellent user experience for testing and interacting with APIs. Built with Tauri, it offers a modern and intuitive interface for developers.
Plunger is a small, native desktop app for checking one API endpoint: paste a URL or a curl command, press Send, and read the response as a collapsible JSON tree. There is no account, no cloud and no telemetry, and no browser CORS limits, so it reaches localhost and intranet...
GetAPI is a native macOS app that simplifies REST API testing by allowing users to import from Postman, make HTTP requests, and view responses in a streamlined interface.
United States
Free browser-based OpenAPI editor from Postman. Design or import a Swagger 2.0, OpenAPI 3.0, or OpenAPI 3.1 spec (YAML or JSON) and see live documentation with inline validation as you type. No signup, no install. Part of Postman's suite of free developer tools at postman.
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