JSON Formatter
Free JSON formatter and validator. Pretty-print JSON with 2 or 4-space indentation, minify it for production, and get clear error messages for invalid JSON.
About the JSON Formatter
A JSON formatter and validator that pretty-prints JSON with 2 or 4-space indentation, minifies it for production, and surfaces the parser's exact error message and position when the input is invalid.
This formatter turns unreadable, single-line JSON into cleanly indented, human-readable structure in one click — or does the reverse, minifying a formatted document back to its most compact form for production payloads. JSON is how systems talk to each other — API responses, configuration files, webhooks, exports — but machines emit it as a single unreadable line.
It's also a validator. The formatter parses your input with the same strict rules every JSON consumer uses, so if there's a problem — a trailing comma, single quotes instead of double, an unquoted key, a stray character — you get the parser's actual error message instead of a silent failure later in your pipeline. Fixing JSON here is much faster than deploying and reading a stack trace.
Formatting runs entirely in your browser: API keys, customer records and internal payloads never leave your machine, which is exactly what you want when debugging production data. Use 2-space indentation (the JavaScript ecosystem default) for reading and code reviews, 4-space when you'll be scanning deeply nested structures, and minify when every byte counts. A practical debugging loop: paste the response from your API client, format to inspect the structure, edit the value you're testing, then minify and send it back. The output downloads as a .json file when it's too large to comfortably copy.
How to use the JSON Formatter
- Paste the JSON you want to format or validate.
- Pick the output mode: pretty-print with 2 or 4 spaces, or minify.
- Click Format to parse and pretty-print; invalid JSON raises the parser's exact error message and position.
- Copy the output, or download it as a .json file when it's large.
Worked example
pasting '{"key":"value"}' and selecting Pretty-print (2 spaces) outputs a multi-line formatted JSON block, making it easy to read.
Frequently asked questions
- Why is my JSON invalid?
- The usual culprits: trailing commas after the last item, single quotes instead of double quotes, unquoted property names, comments (JSON doesn't allow them), and smart quotes pasted from documents. The error message points at the position of the first problem.
- Is my JSON uploaded anywhere?
- No. Parsing and formatting run entirely in your browser with JavaScript's native JSON engine — safe for payloads containing keys, tokens or customer data.
- When should I minify JSON?
- For production traffic and storage: minified JSON strips all whitespace, cutting payload size meaningfully on large documents. Keep the pretty version for humans, ship the minified one to machines.
- Can this formatter handle very large JSON files?
- Yes, it is designed to handle large JSON documents efficiently. For exceptionally large files, you can format them and then download the result directly to avoid clipboard limitations.
- Does it fix common JSON errors automatically?
- It acts as a strict validator and will highlight exactly where an error occurs, but it won't guess your intent to automatically fix issues like missing quotes or trailing commas.
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