Private, Offline JSON Formatter & Diff Checker - {}projson

{}projson

A JSON toolkit that runs entirely in your browser. No server, no sign-up — your data never leaves your machine.

Private by design

All processing happens locally in JavaScript. Nothing is uploaded or transmitted — safe for credentials, internal payloads, or sensitive configs.

Zero dependencies

No frameworks, no build step, no npm packages. The entire toolkit is plain HTML, CSS, and JavaScript — loads instantly and works offline.

Editor-grade interface

Minimap, bracket-pair highlighting, per-line fold toggles, collapse-depth slider, and breadcrumb navigation — built for real JSON, not toy inputs.

Semantic diff

Keys are sorted before comparison, so {"a":1,"b":2} and {"b":2,"a":1} are correctly identified as identical — unlike raw text diff tools.

Format / View

Pretty-print with syntax highlighting and line numbers
Interactive collapsible tree view
Edit JSON inline — re-renders on blur, red tint on invalid
Collapse-depth slider + per-line fold toggles
Clickable breadcrumb navigation
VS Code-style bracket pair highlighting
Minimap with draggable viewport indicator

Escape / Unescape

Escape plain text → JSON string literal
Unescape JSON string literal → plain text
Auto mode — detects direction; minifies before escaping valid JSON

Diff Checker

Semantic diff — sorts keys, strips whitespace before comparing
Falls back to raw text diff for invalid JSON
Fold toggles and breadcrumb on diff output

Frequently Asked Questions

Is my JSON data sent to a server?

No. projson processes everything locally in your browser. Your data never leaves your machine unless you explicitly click the "Share" button.

What makes the diff checker "semantic"?

It automatically parses, sorts keys, and standardizes whitespace before comparing. It only highlights actual structural or value differences.

Does projson work offline?

Yes! Our Service Worker caches the app. You can disconnect from the internet and continue to format, escape, and diff JSON flawlessly.

Can I install this as an app?

Yes! projson is a fully compliant Progressive Web App (PWA). You can install it directly to your home screen or desktop via your browser (Chrome, Edge, Safari) and use it just like a native application.

Vanilla JS · Zero dependencies · Works offline · Dark / light theme · MIT License

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Input

Output

JSON A

JSON B

Diff output

{} projson · Your data never leaves the browser · Zero dependencies · Works offline · MIT License