Built for Developers
Every tool you need for working with JSON, in one clean interface. No signup, no ads, no nonsense.
Format & Beautify
Pretty-print JSON with configurable indentation (2 or 4 spaces). One click or keyboard shortcut.
Minify & Compress
Compact JSON by removing all whitespace. Perfect for APIs, configs, and reducing payload size.
Validate & Auto-Fix
Real-time validation with precise error location. Auto-fix trailing commas, single quotes, comments, and unquoted keys.
Tree Viewer
Explore JSON as a collapsible tree with adjustable depth. Timestamps are automatically detected and displayed as human-readable dates.
JSON Diff
Compare two JSON documents side by side with line-level diff highlighting. Instantly spot what changed.
Keyboard Shortcuts
Format, minify, and copy with keyboard shortcuts. Tab key inserts spaces, not focus change.
Sort Object Keys
Alphabetically sort all keys in JSON for consistent, readable, diff-friendly output.
Import & Export
Import JSON files from disk and download results. Supports .json, .jsonl, .geojson, and .txt files.
100% Private
Everything runs in your browser. No data is sent to any server. Works offline as a PWA.
Keyboard Shortcuts
Frequently Asked Questions
Is my data safe?
Absolutely. JSON Online processes everything locally in your browser. No data is ever sent to a server. You can verify this by opening the Network tab in your browser's Developer Tools — you'll see zero outbound requests with your data.
Can I use this offline?
Yes! JSON Online is a Progressive Web App (PWA). Install it from the browser's address bar or the install button, and it works offline — perfect for development on the go.
What JSON size can it handle?
JSON Online can handle files up to several megabytes. Performance depends on your browser and device, but typical API responses and config files work instantly.
What does Auto-Fix repair?
Auto-Fix handles the most common mistakes: trailing commas, single quotes instead of double quotes, unquoted keys, JavaScript comments (// and /* */), BOM characters, and JS-only literals like undefined, NaN, and Infinity.
How does timestamp detection work?
In the Tree Viewer, numeric values that look like Unix timestamps (seconds or milliseconds) and ISO 8601 date strings are automatically shown with a human-readable date tooltip. No configuration needed.
Is it really free?
Yes, JSON Online is completely free with no hidden fees, no signup, and no ads. It's built for developers who just want a fast, clean JSON tool.