JSON Formatter & Validator

Nothing leaves your device

The formatter uses your browser's native JSON parser, so everything happens locally. Nothing you paste is transmitted, logged or stored — which matters when the JSON is a config file, an API response or anything else you would rather not upload to a stranger's server.

Format, minify or validate

Formatting (or "pretty-printing") adds consistent indentation and line breaks so nested structures become readable. Minifying strips every optional space and newline to produce the smallest valid payload, which is what you want before sending data over the wire. Validating simply confirms the text is well-formed JSON and, if not, points you at the problem.

Why valid-looking JSON gets rejected

JSON is stricter than the JavaScript object syntax it resembles. The most common reasons a paste fails:

• Trailing commas — a comma after the final array item or object property is not allowed.
• Single quotes — strings and keys must use double quotes.
• Unquoted keys — every property name has to be a quoted string.
• Comments — // and /* */ are not part of the JSON standard.

When parsing fails, the error message includes the line and column of the offending character so you are not left hunting through a wall of text.

Frequently asked questions

Is my JSON uploaded anywhere?

No. Formatting, minifying and validation all run in your browser with the native JSON parser. Nothing you paste is sent to a server, logged or stored, so it is safe to use with configuration or API data.

Why does JSON that looks correct fail to validate?

The usual culprits are a trailing comma after the last item, single quotes instead of double quotes, unquoted keys, or JavaScript-style comments. Strict JSON allows none of these. The validator reports the line and column so you can find the exact spot.

What indentation should I use?

Two spaces is the most common convention and keeps files compact; four spaces is easier to read for deeply nested data. Both are offered here, along with tab indentation. It is purely cosmetic and does not change the data.

Does formatting change my data?

No. Formatting and minifying only add or remove whitespace. The keys, values, ordering and structure are preserved exactly; only the presentation changes.