JSON Formatter & Validator Pro
Professional JSON formatting, validation, schema validation, and diff comparison tool
Input JSON
Formatted Output
How to format JSON online?
Format, validate, and beautify JSON data with our professional JSON formatter. Features include syntax highlighting, error detection, schema validation, tree view with search, JSONPath queries, diff comparison, JSONC support, and transform operations. Perfect for API development, data analysis, and debugging workflows.
Features
- Syntax highlighting and collapsible tree view with search
- Full JSON Schema validation with detailed error paths
- Side-by-side diff comparison with color-coded changes
- JSONPath query engine with filters and recursive descent
- JSONC/JSON5 support (comments and trailing commas)
- Transform operations: flatten, unflatten, remove nulls
- Copy/download formatted or minified JSON
How to use
- Paste or upload your JSON.
- Click Format to pretty-print and validate.
- Review errors, then copy or download the result.
Tips & Best Practices
- Always validate your data before processing to catch syntax errors early.
- Use the copy button to quickly transfer formatted output to your clipboard.
- For large files, consider breaking them into smaller chunks for better performance.
- Back up your original data before applying any transformations.
- Use keyboard shortcuts for faster workflow: Ctrl+A to select all, Ctrl+C to copy.
FAQ
Do you store my JSON?
No. All processing happens in your browser. Your data never leaves your device.
Can I validate against a schema?
Yes. Provide a JSON Schema document and run validation. The validator supports type checking, required fields, enum, pattern, min/max constraints, nested schemas, additionalProperties, oneOf/anyOf/allOf, and array item validation with clear error paths.
What JSON formats are supported?
We support standard JSON and JSONC (JSON with Comments). Enable JSONC mode to parse JSON files with line comments (//), block comments (/* */), and trailing commas — common in VS Code settings, tsconfig, and other config files.
Can I format large JSON files?
Yes, but very large JSON files (over 1MB) may cause slower tree view performance. For optimal results, we recommend keeping files under 10MB. You can also use the minify transform to reduce file size.
How does the diff comparison work?
Paste your original JSON in the input and a modified version in the diff tab. Click Compare to see a color-coded unified diff with additions (green), removals (red), and summary statistics.
What JSONPath expressions are supported?
We support: root ($), dot notation (.key), bracket notation (['key']), array indexing ([0]), wildcards ([*]), recursive descent (..key), array slicing ([0:3]), and filter expressions ([?(@.price > 10)]).
Can I customize the formatting?
Yes. You can adjust the indent size (2, 4, or 8 spaces), enable alphabetical key sorting, and toggle between plain text view and an interactive collapsible tree view with search and syntax highlighting.
What transform operations are available?
Flatten converts nested objects to dot-notation keys, Unflatten reverses it, Remove Nulls strips all null values, Remove Empty strips empty strings/arrays/objects, and Minify compresses to a single line.
Can I search within the tree view?
Yes. Use the search box above the tree view to filter and highlight nodes by key name or value. Matching nodes are highlighted and parent nodes auto-expand to show results.
Is my data secure?
Absolutely. All JSON processing happens locally in your browser using JavaScript. No data is transmitted to any server, making it completely safe for sensitive API responses, configuration files, and private data.