{ } JSON Formatter & Beautifier
JSON pretty-print, beautifier, minifier, and validator — all in your browser
✓ Free Forever · ✓ No Signup · ✓ No Upload · ✓ Works Offline
🔒 Your data never leaves your device. All processing happens locally in your browser using JSON.parse + a lossless re-indenter. No upload, no server, no tracking.
Features
- Pretty Print — Re-indent JSON for easy reading. Only the whitespace changes — numbers, escapes and key order stay exactly as written.
- Minify — Compress JSON by removing all whitespace — ideal for APIs and config files.
- Validate — Check if your JSON is valid and see clear error messages for syntax issues.
- Statistics — See key count, nesting depth, and data size at a glance.
How It Works
- Paste your JSON — Enter or paste JSON data in the input area.
- Format or minify — Click Format for pretty-print or Minify for compact output.
- Copy the result — Copy the formatted output to your clipboard.
Use Cases
- Pretty-print API responses for debugging
- Minify JSON config files for production
- Validate JSON before sending to APIs
Frequently Asked Questions
What indentation is used?
Pretty-print uses 2-space indentation, which is the most common standard for JSON formatting.
Can it handle large JSON files?
Yes. The browser's native JSON parser is very efficient. Files up to several MB are handled smoothly.
Notes from Milo 🐨
A formatter should only touch whitespace, and mine didn't: paste an ID like 12345678901234567890 and the "formatted" copy said 12345678901234567000. It also turned 1.10 into 1.1, decoded \u00e9 escapes, and when a key appeared twice it quietly threw one away. Now it re-indents your text exactly as written — every number, escape and key stays put — and tells you if a key is duplicated, since most parsers will keep only the last one. Files saved with a BOM open now, and the key/depth/size counters show real numbers instead of raw template text.
From the blog
- 📖 How to Format, Validate, and Beautify JSON — Pretty-print messy JSON, catch syntax errors with line numbers, and minify for production — all in your browser without uploading API responses full of tokens.
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💬 Bug, idea, or just to say hi? Tell Milo 🐨 · hello@toolkoala.com