A JSON tool that keeps your data yours
jsonduval is a free online tool to format, validate and explore JSON — built around one principle: your data should never leave your device.
Private by design. Every operation — formatting, minifying, validation, the collapsible tree — runs in JavaScript inside your own browser. Your JSON is never sent to a server, never logged, and never stored. There is no backend to upload it to.
What it does
- Format & beautify — turn minified or messy JSON into clean, indented, readable text.
- Minify — collapse JSON to a single line to save space.
- Validate — catch syntax errors instantly, with the exact line and column of the problem.
- Explore — a colour-coded, collapsible tree so you can navigate deep or large structures.
- Copy & download — grab the result in one click.
Why privacy matters here
JSON often contains sensitive things: API responses, config files, tokens, personal records. Many online formatters upload whatever you paste to their servers to process it. jsonduval was built the opposite way — the processing happens locally, so there is nothing to intercept, store, or leak. You can even use it offline once the page has loaded.
Who it's for
Developers, data analysts, QA engineers, and anyone who works with APIs or config files and wants a fast, no-nonsense JSON tool that respects their data.
Try the formatter →