JSON Formatter & Validator
Format, validate, and minify JSON instantly. Syntax highlighting, error detection with line numbers, and collapsible tree view. Runs in your browser — your data never leaves your device.
Fast & Free
Process files up to 100MB at no cost. No account needed.
Secure
Files are encrypted and automatically deleted after processing.
High Quality
Optimized algorithms for the best quality-to-size ratio.
About JSON Formatter & Validator
What JSON is and why formatting matters
JSON (JavaScript Object Notation) is the standard data format for APIs, configuration files, and data exchange between systems. Raw JSON from API responses often arrives as a single unreadable line — thousands of characters with no indentation or line breaks. Pretty-printing it with proper indentation transforms it from an impenetrable wall of text into a structured, human-readable document you can actually debug and understand.
What this tool does
Formats JSON with customizable indentation (2 or 4 spaces), validates syntax and points to exact error locations (line and character position), and minifies for production use by stripping all whitespace. Syntax highlighting makes it easy to distinguish strings, numbers, booleans, and null values at a glance. The stats panel shows key count, nesting depth, and total size.
Privacy
Your JSON data stays in your browser. API responses, config files, and database exports often contain sensitive information — API keys, user data, authentication tokens, internal URLs. Nothing you paste here is ever transmitted to any server. All parsing, formatting, and validation happens locally in your browser's JavaScript engine.
Common uses for JSON Formatter & Validator
- Pretty-printing API responses for debugging during development
- Validating JSON config files before deploying to production
- Minifying JSON payloads to reduce bandwidth in API responses
- Exploring deeply nested JSON structures to understand data shape
- Cleaning up and formatting JSON data exports from databases
Frequently Asked Questions
Can it fix invalid JSON?
It identifies exactly where the error is — line number and character position — but doesn't auto-fix. Common issues include trailing commas, single quotes instead of double quotes, unquoted keys, and missing closing brackets.
What's the difference between format and minify?
Format adds indentation and line breaks for readability — what you want during development and debugging. Minify removes all unnecessary whitespace to create the smallest possible string, which is what you want for production API responses and config files to reduce bandwidth.
Is there a size limit?
No hard limit. The tool handles JSON files up to several megabytes without issues. Extremely large files (10MB+) may cause browser slowdown since all processing happens locally in your browser.
Does it support JSON with comments (JSONC)?
Standard JSON doesn't allow comments. If your JSON contains // or /* */ comments, the validator will flag them as syntax errors. You'll need to strip comments before validating, or use a JSONC-specific tool.