Best API Tools & Testing Apps in 2026

iOS Screen Time from a REST API

API Tools & Testing

We're Oliver and Royce and we're the founders of Clearspace. We build tools to help people reduce their screen time (here’s us two years ago: https://news.ycombinator.com/item?id=35888644 ) We get all kinds of requests from users for ways they'd like to use their scree

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Postman

API Tools & Testing

Accelerate API development with Postman's all-in-one platform. Streamline collaboration and simplify the API lifecycle for faster, better results. Learn more.

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Yaade

API Tools & Testing

Yaade is an open-source, self-hosted, collaborative API development environment. )

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Bijira

API Tools & Testing

We're the team behind Bijira, the new API Management SaaS platform (also AI-enabled) built by WSO2 (you might know us from Choreo, Ballerina, and WSO2 API Manager). Bijira helps dev teams design, deploy, govern, and monitor APIs with minimal friction. It’s especially useful if you're manag

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Apicat

API Tools & Testing

Apicat is the ultimate offline Postman alternative that stores your .http files locally. It’s Git-friendly, open-source, and highly compatible with Postman. Test APIs offline with this powerful free offline API client designed for developers who need a reliable local API testing tool

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Corporate Hierarchy API

API Tools & Testing

Hey HN! I'm sharing our Corporate Hierarchy API that we just launched in beta. Its current focus is on mapping the complete corporate ownership upwards to the ultimate parent by doing deep research across the open web and global government registries. The problem: Companies spend millions on ma

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Nango

API Tools & Testing

Open-source unified API for integrations

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HN Sentiment API

API Tools & Testing

I built an API that extracts entities from Hacker News comments and classifies sentiment towards them as positive, negative, or neutral. It also classifies overall comment sentiment and assigns each entity a label (person, location, date, technology, organization, other). 505k+ comments, Oct 31 - Pr

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Buf

API Tools & Testing

Protobuf and gRPC tooling for API development

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Bruno

API Tools & Testing

Fast and Git-friendly open-source API client

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Hoppscotch

API Tools & Testing

Helps you create requests faster, saving precious time on development.

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Scalar

API Tools & Testing

Beautiful API references from OpenAPI files

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Yapi

API Tools & Testing

I shared a previous version of yapi a few months ago in the comments section of a post talking about the insanity of Postman being 'down'. yapi has developed into a more mature project since then! https://github.com/jamierpond/yapi Still very early, but it makes me mu

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Tako, a Knowledge Search API

API Tools & Testing

I'm Bobby, CTO of Tako. We just launched our Knowledge Search API. Our API takes natural-language prompts like "Nvidia M&A history" and returns visual answers and grounding text sourced from real-time, structured data (example: https://trytako.com/card/YHloo1E

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Insomnia

API Tools & Testing

Leading Open Source API Development Platform for HTTP, REST, GraphQL, gRPC, SOAP, and WebSockets

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Turn APIs into MCP servers without code

API Tools & Testing

Hi HN! We built Zalor. It turns an OpenAPI spec into an MCP server, so you can make your APIs callable by Claude or ChatGPT without writing any code. Here's a list of specs you can try: https://github.com/ZalorAI/test-data/tree/main/openapi , but feel free to

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Tyk

API Tools & Testing

Fast and scalable open source API Gateway. Out of the box, Tyk offers an API Management Platform with an API Gateway, API Analytics, Developer Portal and API Management Dashboard. )

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Gotenberg

API Tools & Testing

Developer-friendly API to interact with powerful tools like Chromium and LibreOffice for converting numerous document formats (HTML, Markdown, Word, Excel, etc.) into PDF files, and more. )

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Voiden

API Tools & Testing

Hey HN! Aldin here, a helping hand to Voiden ( https://voiden.md ) Voiden is a free, offline, Git-native API client. Your API definitions, docs, and tests all live together. It came out of years of frustration: cloud sync lock-in, paywalled basics, bloated UIs, and lag on even simple reque

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Kalendis

API Tools & Testing

Kalendis is an API-first scheduling backend. You keep your UI; we handle the gnarly parts (recurrence, time zones, DST, conflict-safe bookings). What it does: • MCP tool: generates typed clients and API route handlers (Next.js/Express/Fastify/Nest) so you can scaffold calls straight f

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LinkdAPI, the best LinkedIn unofficial API

API Tools & Testing

This API is insane, it lets you get public data in real time and not like most services out there that let you search old, outdated databases

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MCP Generator for Your API

API Tools & Testing

Hey HN, Sagiv from liblab is here. We've been deep in the world of API tooling for years at liblab, primarily focusing on generating SDKs and documentation from OpenAPI specs. Recently, we kept running into a recurring frustration: connecting AI tools to existing APIs is way more complex than i

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