JSON Formatter & Validator
Beautify, minify and validate JSON instantly as you type.
Input
Output
Formatted JSON will appear here
Paste something on the left, or
Tip: output updates automatically as you type. Click Jump to error to find the problem in your input.
About the JSON Formatter
DevNest's JSON Formatter turns messy, single-line or minified JSON into clean, readable, syntax-highlighted output — instantly, as you type. It also works as a JSON validator: if something is wrong, it tells you exactly what the problem is and where it is.
Everything happens locally in your browser using the built-in JSON parser, so API responses, config files and logs you paste here are never uploaded anywhere.
How to use the JSON Formatter
- 1
Paste your JSON
Paste or type JSON into the Input panel, or click Sample to try an example.
- 2
See it formatted instantly
The Output panel updates live and the badge shows whether your JSON is valid.
- 3
Choose a style
Pick Beautify or Minify, set the indent to 2 spaces, 4 spaces or tabs, and optionally sort keys.
- 4
Copy or download
Copy the result to your clipboard in one click, or download it as a .json file.
Frequently asked questions
Is my JSON sent to a server?
No. Your JSON is parsed and formatted entirely in your browser. Nothing you paste is uploaded, stored or logged.
How do I find the error in invalid JSON?
When your JSON is invalid, the Output panel shows the error message, the line and column number, and a preview of the line with a marker under the problem. Click Jump to error to select that exact spot in your input.
What is the difference between beautify and minify?
Beautify adds line breaks and indentation so JSON is easy to read. Minify removes all unnecessary whitespace to make the JSON as small as possible, which is useful for sending it over a network or storing it.
What are the most common JSON syntax errors?
Trailing commas after the last item, single quotes instead of double quotes, unquoted property names, comments, and missing commas between items. JSON does not allow any of these, even though JavaScript does.
What does Sort keys do?
Sort keys orders the properties of every object alphabetically, including nested objects. The order of items inside arrays is never changed. This makes it easier to compare two JSON documents.
Why did a very large number change after formatting?
JavaScript numbers can only represent integers exactly up to 9,007,199,254,740,991. Larger integers, such as some database IDs, lose precision when parsed. Store such values as strings if exact digits matter.
More free developer tools
Base64 Encoder/Decoder
Convert text to Base64 and back, with full Unicode support.
UUID Generator
Generate random v4 UUIDs — one or many — in the format you need.
JWT Decoder
Decode JSON Web Tokens to inspect the header, payload and expiry.
Timestamp Converter
Convert Unix timestamps to dates and dates to timestamps.
URL Encoder/Decoder
Percent-encode and decode URLs, and break down query strings.
Hash Generator
Generate MD5, SHA-1, SHA-256 and SHA-512 hashes of text or files.
Regex Tester
Test regular expressions with live match highlighting and groups.