JSON formatter and validator
Paste JSON below to beautify, validate, and explore it. Formatting starts as soon as you stop typing.
Formatted JSON will appear here.
What this tool does
tidyJSON turns unreadable JSON into something you can actually navigate. Paste a response from an API, a config file, or a log line, and you get an indented, colour-coded tree you can collapse section by section. It also tells you about the two things most formatters hide from you: integers too large for JavaScript to store exactly, and duplicate keys that the parser silently threw away.
Everything happens in your browser
There is no upload step and no server round trip. The page uses the JSON parser built into your browser, so the data in the box stays on your machine even if you close the tab or lose your connection. That makes it safe for payloads you would not paste into a random website: staging credentials, customer records, internal API responses.
Working with large payloads
Long arrays load in batches and nested sections are built only when you expand them, so a multi-megabyte file opens without freezing the tab. Use Collapse all to get an overview of a document's top-level shape, then open just the branch you care about.
Common questions
Is my JSON uploaded to a server?
No. Formatting, validation, and minification all run in your browser. Your data never leaves the page.
What is the difference between beautifying and minifying JSON?
Beautifying adds line breaks and indentation so the structure is readable. Minifying strips every optional space and newline to make the payload as small as possible for storage or transfer. Both describe exactly the same data.
Why did my large ID number change?
JavaScript numbers are 64-bit floats and can represent integers exactly only up to 9,007,199,254,740,991. Longer IDs — the kind Twitter, Discord, and many databases hand out — lose their final digits in any JavaScript-based tool. tidyJSON warns you when it spots one instead of quietly rewriting your data.
What happens to duplicate keys in a JSON object?
The specification does not forbid them, and most parsers keep only the last occurrence, discarding everything before it. tidyJSON scans your input and names the keys that were duplicated.
How big a file can it handle?
Several megabytes. Very long arrays and deep nesting are rendered on demand, so the page stays responsive on large API payloads.