JSON / CSV Formatter
Format, validate and minify JSON with clear error locations, or convert between JSON and CSV instantly.
A free JSON and CSV formatter lets you clean up messy data in seconds. Paste raw JSON to beautify it, validate the structure, or minify it for production. Convert JSON arrays into CSV spreadsheets, or turn CSV files into JSON for your API — all in your browser, with no upload to a server.
REXAI's Formatter handles small snippets and large datasets. Everything runs locally, so sensitive data never leaves your device — safe for internal configs, API responses, and client files.
What You Can Do
Beautify JSON. Turn single-line compressed JSON into indented, readable output with proper nesting. Choose 2-space or 4-space indentation.
Minify JSON. Strip whitespace, line breaks, and comments to shrink file size for production. Perfect before embedding JSON into HTML or sending it over the wire.
Validate JSON. Check for syntax errors — missing commas, unclosed brackets, trailing commas, unquoted keys. See the exact line and column where the problem is.
Convert JSON to CSV. Flatten a JSON array of objects into a CSV table with columns and rows. Auto-detects keys as column headers.
Convert CSV to JSON. Turn a spreadsheet export into a JSON array ready for an API, database, or front-end code.
How to Use the Formatter
1. Paste your data. Drop your JSON or CSV into the input box. For files, copy the content and paste — direct upload isn't required.
2. Choose an action. Pick Format (beautify), Minify, Validate, or Convert (JSON ↔ CSV) at the top.
3. Review the output. The result appears instantly in the output panel with syntax highlighting and error messages where relevant.
4. Copy or download. Copy the result to clipboard or download it as a file.
Common Uses for a JSON Formatter
Debugging APIs. API responses come back as compressed JSON. Beautify them to see the structure clearly.
Editing config files. package.json, tsconfig.json, and similar files are easier to edit when properly indented.
Preparing data for code. Convert CSV exports from Excel or Google Sheets into JSON arrays for your app.
Cleaning spreadsheets. Convert JSON data back to CSV to open in Excel, Google Sheets, or Numbers.
Pre-production optimization. Minify JSON before embedding it in HTML to save bytes.
JSON vs CSV — Which to Use
JSON. Best for nested data, API payloads, config files, and any data with structure. Human-readable, universally supported.
CSV. Best for flat tabular data, spreadsheets, and anything that opens in Excel. Simple, compact, but can't represent nested structures.
When you need to move between them — CSV exports for a client, JSON for your code — this tool handles the conversion in both directions.
Common JSON Errors It Catches
Trailing commas. JSON doesn't allow a comma after the last item in an object or array.
Unquoted keys. JSON requires double quotes around every key. Single quotes and unquoted keys are invalid.
Missing commas. Every item in an object or array must be separated by a comma.
Unclosed brackets. Every opening { or [ needs a matching closing } or ].
Invalid values. Comments, undefined, NaN, and single-quoted strings aren't valid JSON.
Frequently Asked Questions
- Is it free? Yes. Unlimited formatting and conversion, no signup, no watermark.
- Is my data uploaded to a server? No. Everything runs in your browser using JavaScript. Your data never leaves your device.
- Is there a size limit? The tool handles JSON files up to a few megabytes. Very large files (50MB+) may slow down the browser.
- Can it fix broken JSON? It identifies the errors and their exact location. Auto-fixing is limited to whitespace issues — you'll need to correct the syntax manually.
- Does it preserve key order? Yes for JSON. When converting to CSV, columns are ordered by first appearance in the data.
- Can it handle nested JSON? Yes for formatting and validation. For CSV conversion, nested objects are flattened into dotted column names (e.g. user.name).
- What CSV delimiters are supported? Comma and semicolon. Quote-wrapped fields are handled correctly.
- Can I download the result? Yes. Copy to clipboard or download as a .json or .csv file.
- Does it work on mobile? Yes. Fully functional on any modern browser.
Format Your JSON Free
Paste any JSON or CSV above and get a clean, formatted result in seconds. Free, private, and no signup — the way a formatter should work.