JSON Formatter

Runs in your browser

Beautify, minify and validate JSON.

JSON

Formatted

This tool runs entirely in your browser. Your data never leaves your device — nothing is uploaded to our servers.

About JSON Formatter

A JSON formatter earns its place on the day something is broken. Minified API responses arrive as a single 40,000-character line, and the useful question is rarely 'how does this look indented' but 'where exactly is the syntax error'. This formatter parses with the browser's native JSON parser and reports the position of the first failure, so a trailing comma or unquoted key is located rather than guessed at. Everything runs locally, which matters because API responses routinely contain tokens and personal data.

When to use JSON Formatter

Debugging an API response

Paste a minified payload to see its actual structure — where the array of results really begins, and which fields are nested where.

Finding the syntax error in a config file

package.json, tsconfig.json and CI configs fail on a single trailing comma. The parser points at the offending position instead of failing silently.

Inspecting a payload containing credentials

Responses often include bearer tokens or customer records. Pasting those into an unknown server-side formatter is a data-leak incident; here the text stays in your tab.

Limitations worth knowing

Only strict JSON is accepted. Comments, trailing commas and single-quoted strings are valid JavaScript but invalid JSON, and are rejected by design.
Very large documents (tens of megabytes) can make the browser tab unresponsive while parsing.
Key order is preserved as written, but JSON objects are formally unordered — don't rely on it.
Numbers beyond JavaScript's safe integer range lose precision on parse. This affects large IDs, notably Twitter/X snowflake IDs.

How to json formatter

1
Paste your JSON into the input area.
2
Format it to expand the structure with consistent indentation.
3
If parsing fails, read the reported error position and inspect that point in the source — the true mistake is often just before it.
4
Copy the formatted result, or minify it again for transport.

Frequently asked questions

Why does my JSON fail to parse when it looks correct?+

The usual culprits are a trailing comma after the last element, keys without double quotes, single quotes instead of double, or a stray non-breaking space pasted in from a document. All four are legal JavaScript object syntax but invalid JSON, which is why they slip past a visual check.

Is my data sent anywhere?+

No. Parsing and formatting happen in your browser using the built-in JSON parser. This is the main reason to prefer a client-side formatter — API payloads frequently contain access tokens and personal data that should never be pasted into a remote service.

Why did my large ID number change?+

JavaScript stores numbers as doubles, so integers above 9,007,199,254,740,991 cannot be represented exactly and get rounded on parse. If your IDs are that large, they should be transmitted as strings — this is a JSON/JavaScript constraint rather than a bug in the formatter.