JSON Formatter & Validator
Format, validate, minify, and convert JSON data instantly — 100% client-side, nothing leaves your browser.
Dedicated JSON Tools
Use these focused tools for specific JSON operations:
What is the JSON Formatter & Validator?
JSON (JavaScript Object Notation) is a lightweight text format for exchanging data between systems. In its raw form, JSON is often a dense, single-line string with no whitespace — readable by machines, but difficult for humans to scan and debug. JSON formatting, also called pretty-printing, restructures that raw string by adding consistent indentation and line breaks. A deeply nested API response that would otherwise be unreadable becomes a clear hierarchy you can inspect at a glance.
How to use the JSON Formatter & Validator?
- Paste or type your JSON into the input field on the left. The formatter validates your JSON instantly as you type, highlighting any errors in red with a description of what went wrong and which line to check.
- Click 'Format JSON' to pretty-print it with 2-space indentation, or 'Minify JSON' to compress it into a single line.
- For URL-encoded JSON strings, click 'URL Decode & Format' to extract and format in one step.
- Inspect your formatted structure dynamically in the 'Tree View' tab.
- Convert JSON data to comma-separated values in the 'JSON to CSV' tab.
- Use the 'JSON Diff' tab to compare your original raw JSON with your modified version side-by-side.
- Use the 'Copy' button to copy the output directly to your clipboard. Your JSON data never leaves your browser — processing happens entirely client-side with no server requests.
Frequently Asked Questions
Is this JSON formatter safe to use with sensitive data?
Yes. This JSON formatter runs entirely in your browser using JavaScript. Your data is never sent to any server — it never leaves your device. This makes it safe to use with API keys, credentials, internal config files, and any other sensitive JSON data.
What is JSON formatting?
JSON formatting (also called pretty-printing) adds consistent indentation, line breaks, and whitespace to a JSON string so it's easy for humans to read. Unformatted JSON is often a single long line with no whitespace — formatting structures it into a readable hierarchy.
What is the difference between JSON formatting and JSON validation?
Formatting changes how JSON looks (adding spaces and indentation) but doesn't check if it's correct. Validation checks whether your JSON follows the JSON specification — catching missing commas, unmatched brackets, trailing commas, and incorrect quote types. This tool does both.
What does JSON minification do?
JSON minification removes all whitespace, indentation, and line breaks from a JSON string to make it as small as possible. This is useful before sending JSON in API responses or embedding it in source code, as it reduces payload size.
Can I format JSON in JavaScript without a tool?
Yes. In JavaScript, you can format JSON using JSON.stringify(data, null, 2) — the third argument sets the indentation level. To validate, wrap JSON.parse() in a try/catch block. This online tool automates both operations instantly without writing any code.
Why is my JSON invalid?
Common JSON errors include: trailing commas after the last item in an array or object (not allowed in JSON, unlike JavaScript), single quotes instead of double quotes around strings, missing quotes around object keys, unescaped special characters in strings, and comments (JSON does not support comments). This validator highlights exactly where the error is.
JSON Formatter Features
Format & Pretty-Print
Restructures any valid JSON with 2-space indentation and sorted line breaks. Works on JSON of any size, from single objects to deeply nested API payloads.
Validate with Error Detection
Catches the most common JSON mistakes: trailing commas, single-quoted strings, unquoted keys, missing brackets, and unexpected characters. The error message tells you exactly which line to fix.
Minify
Strips all whitespace and newlines to produce the most compact version of your JSON. Use this before including JSON in API responses, environment configs, or source code.
Convert to CSV
Convert JSON to CSV format for use in spreadsheets. Nested keys are flattened (e.g., "address.city") for easy tabular representation.
Syntax Highlighting
Keys, strings, numbers, booleans, and null values are colour-coded for fast visual scanning of your JSON structure.
100% Private
No data is sent to any server. Everything runs in your browser. Safe for API keys, auth tokens, internal configs, and any other sensitive data.
Common JSON Errors and How to Fix Them
Trailing Comma
The most common JSON error. JSON, unlike JavaScript, does not allow a comma after the last item in an array or object.
// ❌ Invalid
{"name": "Priya", "role": "admin",}
// ✅ Valid
{"name": "Priya", "role": "admin"}Single Quotes Instead of Double Quotes
JSON requires double quotes for all strings and keys. Single quotes are valid in JavaScript but not in JSON.
// ❌ Invalid
{'name': 'Priya'}
// ✅ Valid
{"name": "Priya"}Unquoted Keys
All JSON object keys must be wrapped in double quotes, even if they look like valid identifiers.
// ❌ Invalid
{name: "Priya"}
// ✅ Valid
{"name": "Priya"}Comments in JSON
JSON does not support comments. If you need annotated JSON, consider JSON5 or YAML instead.
Unescaped Special Characters
Backslashes, double quotes, and control characters inside string values must be escaped with a backslash.
// ❌ Invalid
{"path": "C:\Users\Priya\Documents"}
// ✅ Valid
{"path": "C:\\Users\\Priya\\Documents"}Related Developer Tools
Working with JSON? These tools on InstantToolsHub pair well with the formatter: