JSON Formatter
Format, validate, minify, and auto-fix JSON online. Instant syntax error detection with line numbers and built-in search.
Our free online JSON Formatter lets you format, validate, minify, and auto-fix JSON in one place. Paste raw or messy JSON and get clean, indented output instantly. The tool detects syntax errors and reports the… Paste or type your input above; results update immediately. The tool runs in your browser and we don't store your data.
About This Calculator
Our free online JSON Formatter lets you format, validate, minify, and auto-fix JSON in one place. Paste raw or messy JSON and get clean, indented output instantly. The tool detects syntax errors and reports the exact line and column number so you can pinpoint issues fast. Use the built-in Fix & Format mode to automatically correct common mistakes like trailing commas, single quotes, unquoted keys, and missing brackets. Both the input and output panels include a search bar with match highlighting and previous/next navigation, making it easy to find specific keys or values in large JSON files. Ideal for API developers debugging responses, back-end engineers inspecting database exports, or front-end developers working with config files.
How It Works
Paste your JSON into the left panel and click Format, Validate, or Minify. The formatter parses the input, checks syntax, and produces the result in the right panel. Format adds proper indentation and line breaks for readability. Validate checks syntax and shows a green "Valid JSON" badge or a detailed error with the exact line and column. Minify strips all whitespace to produce the smallest possible output. Fix & Format goes a step further: it removes comments, converts single quotes to double quotes, wraps unquoted keys, fixes trailing commas, and adds missing closing brackets before formatting. Use the copy button on either panel to grab the content. All processing runs locally in your browser — your JSON data is never uploaded to any server.
How to Use
- Enter your values in the calculator fields above
- Click the calculate button or let the calculator auto-update
- Review your results instantly
- Adjust values as needed to see different scenarios
Frequently Asked Questions
What is JSON and why format it?
JSON (JavaScript Object Notation) is a lightweight data format used by virtually every web API and many configuration files. Raw JSON from APIs or logs is often a single compressed line. Formatting adds indentation and line breaks, making it much easier to read, debug, and edit.
What does Fix & Format do?
Fix & Format automatically corrects common JSON mistakes before formatting. It removes JavaScript-style comments, replaces single quotes with double quotes, adds double quotes around unquoted keys, removes trailing commas after the last item in arrays or objects, and adds any missing closing brackets. This is especially useful when copying JSON from code editors, logs, or documentation that may not be strict JSON.
How do I find a specific key in a large JSON file?
Use the search bar at the top of either panel. Type a key name or value and matching text is highlighted. The match counter shows how many results were found, and the arrow buttons let you jump between matches. The view scrolls automatically to keep the active match in view.
What is the difference between Format and Minify?
Format adds indentation and line breaks so you can read the JSON easily. Minify does the opposite — it removes all unnecessary whitespace to produce the smallest possible string. Use Format while developing and debugging, and Minify when you need to reduce payload size for production, API requests, or storage.
Is my JSON data private?
Yes. All formatting, validation, and minification happens entirely in your browser using JavaScript. Your data never leaves your device and is not sent to any server. This makes the tool safe for working with API keys, tokens, user data, or any other sensitive information.
What if my JSON has errors?
The formatter reports the exact error with its line number and column position, such as "Unexpected token at line 12, column 5." Common issues include missing commas between items, unclosed brackets or braces, trailing commas, and unquoted string keys. You can fix them manually or try the Fix & Format button to auto-correct most problems.
Why Use Our Free JSON Formatter Online?
Our JSON Formatter runs in the browser so you can format, convert, or generate without sending data to our servers. No account needed—paste or type, get your result. We offer more dev tools (JSON, Base64, JWT, UUID, timestamps, and more) in the list below.