REST API Client & HTTP Lab — Free Online Tool

In-browser REST API testing client & HTTP request builder with headers, authentication, query params, response telemetry, and cURL & Fetch code export.

REST API Client & HTTP Lab is part of Developer — Code & Utilities on Rajlabs. It runs entirely in your browser — your files and text are never uploaded to a server. The same tool is available on all three primary hosts: utility.rajlabs.in, tools.rajlabs.in and utils.rajlabs.in. Bookmark https://utility.rajlabs.in/api-tester or install it as a standalone app from your browser.

What you can do

In-browser REST API testing client & HTTP request builder with headers, authentication, query params, response telemetry, and cURL & Fetch code export. With REST API Client & HTTP Lab you get live results as you type, one-tap presets for common cases, copy buttons, download/export (PDF, PNG, CSV, JSON where applicable) and a shareable URL that remembers your inputs. Dark mode and mobile responsiveness are built in — it looks great on phone, tablet and desktop.

How to use

1. Open REST API Client & HTTP Lab at https://utility.rajlabs.in/api-tester.
2. Enter or upload your data — the tool validates and previews instantly in the browser.
3. Adjust presets, then copy, download or share the result. Add ?param=value to the URL to prefill for sharing.

Why this tool is different

• Private & offline: 100% client-side — no data leaves your device. Works on slow networks after first load.
• Accurate & fast: exact constants, Indian formats (crore/lakh, IFSC, bigha) and exam presets where relevant.
• Installable: install REST API Client & HTTP Lab as its own app icon (PWA) — it opens directly to this tool.
• Free & no watermark: unlimited use, no signup, no ads covering content.

Tips

Use the category navigation to discover related tools — for example, after using REST API Client & HTTP Lab try other Developer — Code & Utilities tools from the homepage. If you need a different format, the URL Lab, Code Formatter or Converters can chain your output. Found a bug or want a preset? Open an issue on GitHub — Rajlabs ships updates weekly.

Frequently Asked Questions — REST API Client & HTTP Lab

Is REST API Client & HTTP Lab free to use?

Yes, REST API Client & HTTP Lab is completely free with no limits, no watermark, and no signup. It runs 100% in your browser.

Does REST API Client & HTTP Lab upload my files to a server?

No. REST API Client & HTTP Lab processes everything locally in your browser using Developer — Code & Utilities client-side engines (Canvas, pdf-lib, FFmpeg WASM, Tesseract). Your data never leaves your device.

How do I use REST API Client & HTTP Lab?

Open REST API Client & HTTP Lab at https://utility.rajlabs.in/api-tester, enter or upload your data, adjust presets — results update live. Then copy, download or share via URL. You can also install it as a PWA for one-tap offline access.

How to use REST API Client & HTTP Lab

1. Open REST API Client & HTTP Lab at https://utility.rajlabs.in/api-tester.
2. Enter or upload your data — the tool validates and previews instantly in your browser.
3. Adjust presets, then copy, download or share via URL (?param=value) for reuse. Install as PWA for offline access.

Published 2024-08-15 · Updated 2026-09-18 · Open REST API Client & HTTP Lab · Browse all 145+ tools

Static fallback for crawlers without JavaScript — enable JavaScript for the full interactive REST API Client & HTTP Lab experience. Content uses semantic HTML for accessibility and agent browsing.