JSON Formatter & Validator
Paste messy JSON or a plain list of lines — pretty-print, browse as a tree, and copy paths — private and fully client-side.
Paste JSON or a plain list of lines
Switch to Tree to fold nodes and hover for paths like user.meta.tags[0]. ⌘/Ctrl+Enter formats into Input.
How to format and validate JSON
- Paste JSON (minified or pretty) or a plain list — one item per line.
- Watch Output update automatically when Input is valid.
- Switch Text / Tree — fold nodes, hover for paths, check keys · depth · size.
- Choose 2 or 4 space indent, then Copy, Download, or Format / Minify into Input.
Why a private JSON formatter still matters
API responses and config often arrive as dense one-liners. A client-side formatter makes them readable without pasting secrets into a random uploader. Line-and-column errors make broken JSON fixable quickly; minify shrinks payloads; a plain line list can become a JSON array; and Tree view helps you explore nested structures and copy exact paths without leaving the browser.
FAQ
Is my JSON uploaded or stored?
No. Parsing and formatting run in your browser. DevDock does not send your data to a server to use this tool.
Can I paste a plain list instead of JSON?
Yes. Put one item per line (for example one, two, three). The tool turns that into a JSON string array automatically.
I copied from Chrome DevTools Payload and got key, colon, and value on separate lines — can you fix that?
Yes. When the paste is clearly key / : / value triples (common in the Payload panel), the tool rebuilds a JSON object. Ordinary line lists without that pattern still become arrays.
What is the Tree view for?
Tree lets you fold and expand objects and arrays, hover a node to see its path (like user.meta.tags[0]), and copy that path. Text view stays best for copy-paste of the full document.
Why is Output updating while I type?
As soon as Input is valid JSON — or a plain line list — Output shows the pretty-printed result. Use Format into input if you want the pretty version back in Input.
What if my JSON is invalid?
You’ll see Invalid with the line and column of the first problem. Fix that spot and Output will appear again.
Generate mock payloads with the JSON / Mock Data Generator, convert configs with YAML ↔ JSON, or turn tables into objects with CSV ↔ JSON.