JSON
Format, validate, auto-repair, search, and inspect JSON online — free, with precise line and column error locations. Runs entirely in your browser.
What is a JSON formatter and validator?
JSON (JavaScript Object Notation) is the standard format for exchanging data between APIs, config files, and frontend/backend services. A JSON formatter takes minified or messy JSON and re-indents it into a readable structure, while a validator checks the text against the JSON specification and points out exactly where it breaks — a missing comma, an unescaped quote, a trailing comma after the last array item, and so on.
This tool combines both, plus an auto-repair engine for the errors that show up most often when JSON gets pasted from logs, hand-edited, or generated by another language.
How to format and validate JSON online
- Paste or type your JSON into the editor on the left.
- Errors appear inline and in the Results panel with the exact line and column — click any error to jump to it.
- Use Format to pretty-print, Minify to compress, or Sort keys to normalize key order for diffing.
- If the JSON won't parse at all, click Fix it to auto-repair common syntax mistakes.
- Decoding a Base64 string in the Base64 tool that turns out to be JSON? It shows up there already formatted in an embedded copy of this same editor.
Frequently asked questions
Does this JSON formatter send my data to a server?
No. Parsing, formatting, validating, and repairing all happen locally in your browser using a bundled Monaco editor and JSON engine. Nothing you paste is ever uploaded, logged, or stored remotely.
Can it fix invalid JSON automatically?
Yes. The "Fix it" button runs an auto-repair pass that handles common mistakes — trailing commas, single-quoted strings, unquoted keys, missing commas, and comments — and shows you a diff before applying the fix.
What's the difference between formatting and minifying?
Formatting re-indents JSON with consistent spacing so it's easy to read. Minifying strips all non-essential whitespace to produce the smallest possible payload, which is useful before sending JSON over the network.
Can I search inside deeply nested JSON?
Yes. The search box matches keys, values, or both, and each result shows the exact path to that node plus its line and column so you can jump straight to it in the editor.
Is there a file size limit?
Because everything runs client-side, the only real limit is your browser's available memory — there's no server-side upload cap to worry about.