Free JSON Formatter & Validator Online
Format, minify, and validate JSON data online. Paste your JSON to beautify it with proper indentation or compress it.
JSON (JavaScript Object Notation) is the dominant data format for APIs and configuration files, but minified JSON — one long line with no whitespace — is nearly impossible to read by eye. This formatter takes any valid JSON and rewrites it with consistent indentation so you can see the structure, spot missing commas, and diff it meaningfully. It can also do the opposite: strip every unnecessary byte to produce compact JSON for transport. The validator runs in parallel — if your input is malformed, you will see the line and column where the parser rejected it. Everything happens in your browser, so sensitive API responses and tokens never leave your device.
JSON Formatter
How to use this json formatter & validator
- Paste your JSON into the input box. It can be a single object, an array, or a deeply nested structure.
- Click Format to pretty-print the JSON with 2-space indentation.
- Click Minify to strip non-essential whitespace — useful before pasting into a URL parameter or environment variable.
- If the JSON is invalid, the error message points at the line and column where parsing failed. Fix that character and try again.
- Click Copy to put the result on your clipboard.
Common use cases
- Reading an API response that came back on a single line
- Debugging a webhook payload or a log line that contains embedded JSON
- Preparing JSON for inclusion in a config file where indentation matters
- Compressing a JSON blob before pasting it into an environment variable or URL
- Checking whether a string is valid JSON before embedding it in code
Frequently asked questions
Is my JSON data private?
Yes. Parsing, formatting, and validation all happen in your browser using the native JSON parser. Nothing you paste is sent over the network or logged. You can safely paste JSON that contains API keys, production tokens, or personal data — it never leaves your device.
Why is my JSON invalid?
The most common mistakes are trailing commas (valid in JavaScript, invalid in JSON), single quotes instead of double quotes around keys and strings, unquoted keys, and unescaped backslashes or newlines inside strings. The error message will point at the offending character.
Can this handle large JSON files?
The formatter works on strings of several megabytes without trouble. For JSON measured in hundreds of megabytes the browser may slow down or run out of memory — at that size you'd typically stream the file with a command-line tool like jq instead.
What is the difference between JSON and JSON5?
JSON5 is a superset of JSON that allows trailing commas, comments, unquoted keys, and a few other niceties. This tool validates against strict JSON (RFC 8259), so if you paste JSON5 the extras will be flagged as errors.
Does this tool sort keys?
No — the default preserves the original key order, since key order is often meaningful to humans reading the output. Most JSON consumers treat key order as insignificant, so the pretty-printed result is semantically equivalent regardless.