🧾 JSON Formatter & Validator

Paste JSON from an API, a config file or a log. Make it readable, make it small, or find the exact spot where it is broken.

What this tool does

JSON is the text format most apps and websites use to send data. It is easy for computers but hard to read when it is all on one line. This tool adds line breaks and indents (beautify), removes them again (minify), sorts the keys, and checks that the JSON is valid. If it is broken, it tells you the line and column and gives a tip about the most common mistakes.

How to use it

1. Paste your JSON into the first box.
2. Tap Format / Beautify to make it readable, or Minify to make it as small as possible.
3. If you see a red message, go to the line and column it shows and fix that spot.
4. Copy the result or download it as a .json file.

How to read the result

A green ✓ Valid JSON means the data can be read by any program. A red message gives the error from your browser plus the position. The byte numbers show how much smaller minified JSON is — useful when you send data over slow mobile internet.

When it is useful

• Reading an API response while you build a website or app.
• Checking a config file (like manifest.json for a PWA) before you upload it.
• Finding the one missing comma in a long file.
• Making JSON smaller before you put it on a live server.

What it cannot do

• It does not accept comments, single quotes or trailing commas — those are not allowed in real JSON (JSON5 is a different format).
• It does not check if the data is correct for your app (that needs a JSON schema).
• Very big numbers (more than 15–16 digits) can lose precision in the browser.
• Duplicate keys: only the last value is kept after formatting.

Privacy: everything runs inside your browser. Your text is not sent to our server and is not saved.

Questions people ask

Is my JSON sent to a server?

No. Everything happens in your browser with the built-in JSON.parse. Your data never leaves your device.

What are the most common JSON errors?

A comma after the last item, single quotes instead of double quotes, keys without quotes, and a missing } or ]. The tool shows tips for these.

What does minify mean?

Minify removes all spaces and line breaks that are not needed. The data stays the same, the file just gets smaller.

Can I add comments to JSON?

No. Standard JSON does not allow comments. Many people add a field like "_note" instead.

Why did my large number change?

JavaScript can store whole numbers exactly only up to 9,007,199,254,740,991. Bigger IDs should be stored as text in quotes.

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