Free JSON Formatter, Validator & Beautifier
Format, validate, beautify, and minify JSON online. Fix broken JSON automatically. Explore data with a collapsible tree view. Export JSON to CSV. See exact error line numbers. All free, no signup, no ads — runs entirely in your browser.
How to Format and Validate JSON Online
1. Paste your JSON into the input box. Paste raw API responses, minified config files, or any JSON string. The tool validates your JSON instantly as you type.
2. Click Format / Beautify to pretty print your JSON with proper indentation. Choose 2 spaces, 4 spaces, or tab indentation to match your project style.
3. Switch to Tree View to explore deeply nested structures. Click any object or array to expand or collapse it. Perfect for navigating large API responses.
4. Fix broken JSON with one click. The auto-fixer repairs trailing commas, single quotes, comments, and unquoted keys — the four most common JSON syntax errors.
5. Export, copy, or download. Copy formatted or minified JSON to your clipboard. Download as a .json file. Export array data to CSV for spreadsheets.
Everything You Need in One JSON Tool
Most developers use 3-4 different tools to work with JSON. This one does it all.
Pretty print JSON with 2-space, 4-space, or tab indentation. Matches your project conventions. Formats instantly — no waiting, no loading.
Validates against RFC 8259 with exact error messages and line numbers. Catches missing commas, mismatched brackets, invalid strings, and malformed numbers.
Compress JSON by removing all whitespace. Reduces payload size for API responses, config files, and data transfer. One-click copy of minified output.
Auto-repair trailing commas, single quotes, JavaScript comments, and unquoted keys. Fixes the 4 most common reasons JSON parsing fails.
Explore JSON as an interactive tree. Expand and collapse objects and arrays. Navigate deeply nested structures without scrolling through walls of text.
Convert JSON arrays to CSV files. Nested objects are flattened with dot notation. Open in Excel, Google Sheets, or any spreadsheet tool.
See total keys, nesting depth, and type counts (objects, arrays, strings, numbers, booleans, nulls). Understand the shape of your data at a glance.
All processing happens in your browser. Your JSON never leaves your device. No data is logged, stored, or transmitted. Zero server calls.
When to Use a JSON Formatter
Debugging API responses: Paste raw JSON from Postman, curl, browser DevTools, or server logs. Format it instantly to find the field you need. Use tree view for deeply nested responses.
Validating JSON config files: Check package.json, tsconfig.json, .eslintrc.json, and other config files for syntax errors before deploying. Catch missing commas and brackets before they break your build.
Fixing JSON from AI tools: ChatGPT, Claude, and other AI tools sometimes output JSON with trailing commas, comments, or single quotes. Paste it here and click Fix to clean it up automatically.
Optimizing API payloads: Minify JSON before sending it in API requests or storing it in databases. Smaller payloads mean faster transfers and lower bandwidth costs.
Converting JSON to spreadsheets: Export JSON arrays (API data, database exports, webhook payloads) to CSV for analysis in Excel or Google Sheets. No code required.
Learning and teaching JSON: Use the tree view to visualize JSON structure. See exactly how objects nest, how arrays contain items, and how different data types are represented.
Comparing JSON structures: Format two JSON documents with the same indentation, then use a text diff tool (like our Text Diff tool, coming soon) to spot the differences.
Common JSON Errors and How to Fix Them
Trailing Commas
{ "a": 1, "b": 2, }Remove the comma after the last property. The Fix JSON button does this automatically.
Single Quotes
{ 'name': 'John' }JSON requires double quotes for all strings and keys. Fix JSON converts single quotes to double quotes.
Unquoted Keys
{ name: "John" }All keys must be wrapped in double quotes. Fix JSON adds quotes to bare keys automatically.
Comments in JSON
{ "port": 3000 // dev server }Standard JSON does not support comments. Fix JSON strips single-line (//) and multi-line (/* */) comments.
Missing Commas
{ "a": 1 "b": 2 }Each property must be separated by a comma. The validator shows the exact line where the comma is missing.
Mismatched Brackets
{ "items": [1, 2, 3 }Every opening bracket [ or brace { must have a matching closing bracket ] or brace }. The validator identifies the mismatch location.
Frequently Asked Questions
What does this JSON formatter do?
It formats (beautifies), validates, minifies, and fixes JSON in your browser. You can pretty-print with 2 spaces, 4 spaces, or tabs. It also provides a collapsible tree view, detailed error messages with line numbers, JSON stats (keys, depth, types), and CSV export for array data.
How do I validate JSON online?
Paste your JSON into the input box. The tool instantly validates it against the JSON specification (RFC 8259). If valid, you see a green checkmark with key and depth stats. If invalid, you see the exact error message and the line number where the problem occurs.
Can this tool fix broken JSON?
Yes. Click the 'Fix JSON' button to automatically repair common issues: trailing commas, single quotes instead of double quotes, JavaScript-style comments, and unquoted keys. The tool parses the fixed JSON and formats it if successful.
How do I pretty print JSON?
Paste your minified JSON into the input, choose your indentation (2 spaces, 4 spaces, or tabs), and click 'Format / Beautify'. The output is instantly formatted with proper indentation and line breaks. Click 'Copy Formatted' to copy the result.
How do I minify JSON?
Paste your JSON, then click 'Minify'. All whitespace, indentation, and line breaks are removed to produce the smallest possible JSON string. This is useful for reducing payload size in API requests and configuration files.
Can I export JSON to CSV?
Yes. If your JSON contains an array of objects, click 'Export CSV' to download a CSV file. Nested objects are flattened using dot notation (e.g., 'address.city'). The CSV can be opened in Excel, Google Sheets, or any spreadsheet application.
What is the tree view?
The tree view displays your JSON as a collapsible hierarchy. Click the arrow next to any object or array to expand or collapse it. This makes it easy to navigate deeply nested structures and understand the shape of your data without scrolling through thousands of lines.
Does this tool handle large JSON files?
Yes. All processing happens in your browser using native JavaScript parsing, which handles files up to several megabytes without issue. There is no file upload or server processing, so performance depends only on your device.
Is my JSON data sent to a server?
No. All formatting, validation, fixing, and conversion happens entirely in your browser. Your data never leaves your device. Nothing is logged, stored, or transmitted.
What JSON errors can the validator detect?
The validator detects all JSON syntax errors including: missing or extra commas, mismatched brackets and braces, unquoted keys, single quotes instead of double quotes, trailing commas, invalid escape sequences, and malformed numbers. Each error includes a description and approximate line number.
Can I use this as a JSON lint tool?
Yes. This tool functions as a JSON linter — it checks your JSON for syntax errors and reports them with line numbers, similar to JSONLint. It goes further by also offering formatting, minification, tree view, fix, and CSV export in one tool.
What is the difference between JSON formatting and JSON beautifying?
They are the same thing. Formatting (also called beautifying or pretty printing) adds indentation and line breaks to make JSON human-readable. Minifying is the opposite — it removes all whitespace to reduce file size.
More Free Developer Tools
Format JSON here, then use our other tools to encode strings, convert text case, clean text, count words, or remove duplicates.