API Checker - Free Postman Alternative Built Entirely with v0

[jessin (Jessin Sam)]

Hey Vercel Community!

I’m excited to share API Checker (apichecker.io) - a completely free, open API testing platform that I built entirely using v0!

What is API Checker?

API Checker is a modern alternative to Postman designed for developers who want a simple, powerful, and completely free tool to test REST APIs. No signup required, no limitations, 100% free forever.

Key Features

- Request Configuration - Support for all HTTP methods (GET, POST, PUT, DELETE, PATCH)

- Query Parameters UI - Easy-to-use interface instead of manual URL formatting

- Authentication Helpers - Built-in support for Bearer tokens, API keys, and Basic Auth

- Environment Variables - Switch between dev/staging/prod with custom variables using `{{VARIABLE_NAME}}` syntax

- Save & Organise - Save up to 50 requests with collections

- Export/Import - Download and share your API collections as JSON

- cURL Import - Paste any cURL command and auto-populate all fields

- Code Generator - Generate JavaScript, Python, and cURL code snippets

- Response Tools - View headers, search within responses, and compare multiple responses side-by-side

- Performance Metrics - Track response times, success rates, and test history

- Dark Mode - Beautiful light/dark theme toggle

Built 100% with v0

This entire project was built using v0 - from the UI components to the API routes. The development experience was incredible:

- Rapid prototyping - Went from idea to production in record time

- Beautiful UI - Leveraged shadcn/ui components with Tailwind CSS v4

- Type-safe - Full TypeScript support throughout

-*Responsive - Mobile-first design that works perfectly on all devices

- Next.js 15 - Built on the latest Next.js App Router

Tech Stack

- Next.js 15 (App Router)

- React 19

- TypeScript

- Tailwind CSS v4

- shadcn/ui components

- next-themes for dark mode

- Deployed on Vercel

Privacy First

- No data collection or tracking

- Everything is stored locally in the browser

- No signup or registration required

- Completely open and transparent

Try it out!

Live Demo: www.apichecker.io

I’d love to hear your feedback and suggestions for new features! What API testing features would you like to see next?

-–

Made with by Jessin