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12
kinds of mistake fixed
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bytes sent anywhere
What it does

What JSON Studio does.

JSON is strict: one trailing comma or a single quote and a parser refuses the whole file, often with an unhelpful message. JSON Studio shows the line, column and cause of an error, and repairs the usual mistakes in one click, listing each fix.

You paste your JSON once and it follows you from the formatter to the tree viewer, the diff and the converters. Very long numbers, like a 20 digit id, are kept exactly as written instead of being rounded. All of it runs in your browser tab.

Format and minify

Indent with 2 spaces, 4 spaces or tabs, sort keys, and keep short lists on one line. Minify puts everything on one line and shows how much smaller it got.

users.json · json studioFormatted
{
"users": [{
"id": 90071992547409931234, // not rounded
"email": "ada@lindqvist.dev", "verified": true,
"roles": ["admin", "dev"], "plan": null
}]

Errors that point at the cause

The validator gives the line, column and reason. A missing closing quote is reported where the string starts, and an unclosed list names the line it opened on.

One-click fixes

Trailing commas, comments, single and curly quotes, unquoted keys, Python True and None, JavaScript undefined and NaN, missing commas and leading zeros are fixed together, and each fix is listed.

Tree viewer

Fold and unfold objects, search keys and values, and copy the JSONPath or the value of any item.

A diff by data, not text

See what was added, removed and changed, by path. Key order and spacing are ignored, 1.0 equals 1, and list items can be matched by their id.

Converters

Convert to and from CSV (nested objects become columns like address.city) and YAML, and write XML or TypeScript interfaces. Fields missing from some items become optional in TypeScript.

In a minute

See JSON Studio in action.

A short video of JSON Studio doing its one job, from an empty screen to the finished result.

Video coming soonJSON Studio in a minute
How it works

How to use JSON Studio in three steps.

Best for: you want to check, clean up, compare or convert JSON quickly, without pasting data into a site that sends it to a server.

01

Paste your JSON

Paste or type JSON into the editor, or press Ctrl+Enter to format it right away.

02

Fix what is wrong

Read the error or warning and click the fix button if the usual mistakes are found.

03

Pick a tool

Switch to the tree, diff or a converter, and your document comes along without pasting again.

Questions

JSON Studio questions, answered.

How do I fix invalid JSON?

Find the first error and correct it, because a parser stops at the first problem. The most common causes are a trailing comma after the last item, single quotes instead of double quotes, keys without quotes and comments, none of which JSON allows. JSON Studio shows where the error is and can repair these mistakes in one click.

Why does my JSON formatter change long numbers?

Most formatters read numbers with JavaScript, which cannot hold integers above about 9 quadrillion exactly, so a long id gets rounded. For example, 90071992547409931234 turns into 90071992547409930000. JSON Studio keeps numbers as written and warns you when a number is too long for most tools.

Is my JSON sent anywhere?

No. Every page works in your browser and there is no server that receives your data. Your latest input is kept in your browser's local storage so it is still there when you come back, and a share link carries the compressed JSON in the part of the address after #, which browsers do not send to a server.

How do I convert JSON to CSV?

Open the CSV page, paste a JSON array of objects, and download or copy the result. Each object becomes a row, and nested objects are flattened into columns such as address.city. You can choose a comma, semicolon, tab or pipe as the separator, and CSV converts back to nested JSON too.

Does it find duplicate keys?

Yes. JSON that is technically valid can still repeat a key in the same object, and most parsers silently keep only the last one. JSON Studio flags each duplicate key so you can see which value would win.

How big a file can it handle?

Files of tens of megabytes work in a modern browser. Very large output is shown without syntax colours so the page stays fast.

Coming 6 Dec 2026

JSON Studio is on its way.

It opens on 6 Dec 2026. Everything above is what it will do.

See the release plan
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About the toolOpens Nov 22
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