JSONaut — Online JSON Viewer, Formatter, Validator & Repair Tool

JSONaut is a fast, private, entirely in-browser JSON toolbox. Paste text or open a file to view, format (beautify), minify, validate, and repair broken JSON — then explore it as an interactive tree, search keys and values, run JSONPath queries, and transform fields. Everything runs on your device; your data never leaves the browser.

What you can do with JSONaut

Format & beautify JSON with configurable spaces or tabs, or minify to one line.
Validate JSON instantly, with the exact error line and column.
Repair broken JSON — single quotes, trailing commas, unquoted keys, comments, and even JSON embedded in log lines.
Explore an interactive tree — search, edit inline, right-click to copy, duplicate or delete, with color swatches for hex/rgb values.
Query with JSONPath and transform — pick fields to keep or flatten to a values array, then map each item with a JavaScript expression.
Sort keys, stringify, and unescape, with one-click copy and download.

Frequently asked questions

Is JSONaut free?

Yes — JSONaut is completely free to use, with no sign-up required.

Is my JSON data private?

Yes. All parsing, formatting, validation, repair, and queries run locally in your browser. Your JSON is never uploaded to any server.

Can it fix invalid or broken JSON?

Yes. JSONaut detects invalid JSON and offers a one-click fix for common problems like single quotes, trailing commas, unquoted keys, comments, and truncated documents — and can even extract JSON out of log files.

Does it work on large files?

Yes. Parsing runs in a background worker and the tree view renders only visible rows, so JSONaut stays fast on multi-megabyte documents.