Free developer tools that run in your browser
API tester, JSON viewer, regex, image tools, and more. No signup, no installs, and nothing you do ever leaves your device.
Find a tool
Search 19 free tools by name, or by what you need to do.
Most popular
Code & Dev
6 toolsAPI Request Tester
Test REST APIs with full HTTP method support and response visualization
JS to JSON Converter
Convert JavaScript objects to properly formatted JSON with syntax validation
Regex Tester & Generator
Test regular expressions with real-time matching and common pattern snippets
JSON Viewer & Beautifier
Format, validate, and explore JSON with syntax highlighting and tree view
Cron Expression Generator
Generate cron expressions with visual interface and common presets
Base64 Image Converter
Convert images to Base64 strings and decode Base64 back to images with instant preview
Image & Design
7 toolsImage Annotator
Upload images and add annotations with arrows, shapes, text, and freehand drawing
Color & Gradient Converter
Visual color picker with format conversion and gradient generator for all platforms
Image Compressor & Converter
Compress and convert images between formats with drag-and-drop interface
Image Resizer
Resize images with presets, batch processing, and maintain aspect ratios
Color Palette Extractor
Extract dominant colors from uploaded images and get hex color codes
Favicon Generator
Convert images to favicon files (.ico) with multiple sizes (16x16, 32x32, 48x48)
Image Crop Tool
Crop images with precision using our free photo cropper, set aspect ratios, zoom, rotate, resize image, and enjoy advanced editing features in the online image cropper.”
UI & Layout Design
1 toolUtility & Productivity
2 toolsWhy Developers Trust JustInBrowser
Built for speed, privacy, and momentum. Pick a tool, get the result, move on. No installs, no tracking, no nonsense.
For Developers
Skip the busywork. Handle the quick stuff (JSON, regex, Base64, API calls) and get back to shipping features.
For Designers
Try palettes, gradients, and quick image tweaks right in the browser—without bouncing between apps.
For Teams
Share results, stay aligned, and keep things lightweight—especially when everyone’s remote.
Start using tools that don’t slow you down
No signups. No setup. Just open a tool and get back to work.
Lightning Fast
Runs in your browser, so results show up fast.
Always Free
No subscriptions. No upsells. If it’s here, it’s free.
Privacy First
Your data stays on your device. We don’t track you.
Frequently asked questions
Is JustInBrowser free to use?▾
Yes. Every tool is completely free with no subscription, no account, and no upsells.
Is my data safe?▾
Yes. The tools run locally in your browser, so your data stays on your device and is never uploaded to a server.
Do I need to install or sign up for anything?▾
No. Everything runs in the browser — open a tool and start using it immediately, no installs or signup required.
What tools does JustInBrowser offer?▾
A growing set of developer and design tools including an API tester, JSON viewer, regex tester, cron generator, QR/barcode generator, color tools, and image tools (compress, resize, crop, annotate, favicon, Base64).