Format, validate, minify and beautify JSON data online. Syntax highlighting, error detection, and stats — all in your browser with no data ever sent to a server.
Instantly format minified JSON into readable, indented structure
Check if JSON is valid with clear error location messages
Compress formatted JSON back to minimal single-line format
Color-coded output makes JSON structure easy to read and debug
Copy formatted or minified JSON to clipboard instantly
Your JSON data never leaves your browser — 100% private
Paste your raw or minified JSON into the input area.
Click Format JSON to prettify and validate the structure.
If invalid, the error message shows the exact line and issue.
Click Minify to compress back to single-line format for production.
Click Copy to copy your formatted or minified JSON.
JSON (JavaScript Object Notation) is the universal data-interchange format of the modern web. Every major API, from Twitter to Stripe to Google Maps, returns data in JSON format. When applications communicate data — user profiles, product listings, search results, authentication tokens — they package it as JSON.
The problem is that JSON from APIs and production systems is often minified — all the whitespace removed to save bandwidth. This makes it completely unreadable for humans. A single line of minified JSON could contain hundreds of nested properties. Formatting (or beautifying) JSON restores proper indentation and line breaks, transforming unreadable compressed code into clean, debuggable data.
This free online JSON formatter handles both directions: expand minified JSON for readability, or compress formatted JSON for production use. It also validates your JSON syntax and highlights exactly where any errors occur.
The tool shows color-coded syntax highlighting: keys in purple, strings in green, numbers in amber, booleans in blue, and null values in grey — making it easy to scan and debug complex JSON structures.
"key" not 'key'{"a":1,"b":2} not {"a":1,"b":2,}null, not JavaScript's undefined// or /* */ comments"Hello World" (must use double quotes)42, 3.14, -7, 1e10true or false (lowercase)null (lowercase)[1, "two", true, null]{"key": "value"}| Use Case | Format / Beautify | Minify |
|---|---|---|
| Development & debugging | ✅ Essential | ❌ Avoid |
| Production API responses | ❌ Wasteful | ✅ Recommended |
| Config files (human-edited) | ✅ Preferred | ❌ Avoid |
| Documentation & examples | ✅ Required | ❌ Unreadable |
| Data transfer over network | ❌ Larger payload | ✅ Faster |
JSON (JavaScript Object Notation) is the universal data format used to exchange information between web applications and APIs. Minified JSON removes all whitespace for efficiency, making it unreadable. Formatting (beautifying) adds proper indentation and line breaks, making it easy for developers to read, debug, and edit — especially when analyzing API responses or configuration files.
Common JSON errors include: missing or extra commas between properties, using single quotes instead of double quotes (JSON requires double quotes), missing closing brackets or braces, trailing commas after the last item, and using undefined values. Paste your JSON and click Validate — the tool shows the exact error message and character position to help you fix it quickly.
Formatting (beautifying) adds spaces and line breaks for human readability — ideal for development and debugging. Minifying removes all unnecessary whitespace for the smallest file size — ideal for production APIs and better web performance. Minified JSON is typically 20-40% smaller than formatted JSON, reducing bandwidth and speeding up API responses.
Yes. All JSON processing happens entirely in your browser using JavaScript. Your data is never sent to any server, stored, or logged. This makes it safe to use with sensitive JSON like API configurations, authentication tokens, and private data records. The tool works offline once the page is loaded.
No. Standard JSON does not support comments — this is a deliberate design decision. Including // or /* */ comments will cause a parse error. If you need JSON with comments for configuration files, use JSONC (JSON with Comments), which is supported by VS Code and some other tools. For standard JSON APIs, all comments must be removed.
Paste your raw JSON string into the input area. The tool automatically detects whether it's valid or invalid, displays syntax errors with line numbers, and beautifies/formats the JSON with proper indentation (2 or 4 spaces). Use the Minify button to compress JSON for production. Use Collapse to fold nested objects.
Unformatted JSON from APIs, databases, and logs is nearly impossible to read. A single missing comma or mismatched bracket makes JSON invalid and breaks applications. This tool formats and validates JSON instantly, highlights exactly where errors occur, and helps developers debug faster without manual inspection.
Missing comma: Each key-value pair except the last must end with a comma. Trailing comma: JSON does not allow a comma after the last item (unlike JavaScript). Unquoted keys: JSON requires all keys to be in double quotes. Single quotes: JSON requires double quotes, not single quotes. Wrong escape: Use \n for newline, \t for tab, \\ for backslash. Undefined/NaN: JSON doesn't support JavaScript's undefined or NaN values.
JSON formatting is a daily task for developers and increasingly for non-technical users working with APIs, configuration files, and data exports. Here are three practical scenarios:
Scenario 1 — API Debugging: You're integrating a payment API and receive a 400 Bad Request. The raw response is minified: {"error":{"code":"invalid_amount","message":"Amount must be positive","field":"amount","received":-50}}. Paste it into this formatter and the nested structure becomes instantly readable — the "amount" field received −50, which the API rejects. Formatted JSON cuts debugging time from minutes to seconds.
Scenario 2 — Configuration File Validation: A broken package.json prevents npm install from running. The error says "Unexpected token" but no line number. Common culprits: trailing commas after the last property (valid in JavaScript, invalid in JSON), single quotes instead of double quotes, unquoted property names, or a missing closing brace. Pasting into a formatter immediately highlights the exact character causing the parse failure.
Scenario 3 — Data Structure Inspection: You export database records to JSON for a migration project. The raw export is a single-line 50KB minified string. Formatting it exposes the full nesting hierarchy, lets you verify field names match the target schema, and identifies null values or unexpected data types — problems that cause silent migration failures if not caught before import.
{"a":1,"b":2,} fails in JSON (though it's valid JavaScript). Always remove the trailing comma after the last item in objects and arrays."key": "value" not 'key': 'value'. Single quotes cause immediate parse failure.{key: "value"} is invalid; {"key": "value"} is correct. Unquoted keys are a JavaScript convenience not available in JSON.// inline or /* block */ comments. Use JSON5 or JSONC if comments are needed (e.g., VS Code settings.json files).null to represent missing or undefined numeric values.undefined. Properties with undefined values are silently omitted during JSON.stringify().Content-Type: application/json. Missing this header causes many APIs to reject the payload or parse it incorrectly.{"name": null} and a JSON object without a "name" key at all are semantically different. Many APIs treat them differently — check documentation.