How to Format, Validate & Repair JSON Online — Free Tool
Beautify, minify, validate, sort keys, and repair broken JSON. Free formatter with interactive tree view and error detection — 100% browser-based.
Minified JSON from APIs is unreadable. A single missing comma breaks your entire config file. And that JSON your colleague pasted in Slack? It has JavaScript comments and single quotes — invalid JSON, but easily fixable.
The JSON Formatter solves all three in one click.
Format (Beautify)
Paste minified JSON → get 2-space indented, readable output. Perfect for inspecting API responses, config files, and data exports.
Validate
The tool detects JSON syntax errors instantly — shows you the exact line and character where the error is. No more hunting for missing commas.
Repair
Fix the most common JSON issues: trailing commas, unquoted keys, single-quoted strings, JavaScript-style comments. The Repair button auto-fixes these and returns valid JSON.
Pro tip: After formatting JSON, use the JSON to TypeScript converter to generate typed interfaces for your codebase.
FAQs
Does my JSON leave my device?
No — all parsing, formatting, and validation run in your browser. Sensitive payloads never touch any server.
Can it handle large JSON files?
Yes — 5-20 MB JSON files work well. Very large files (>50MB) may freeze the tab — split them first.