No upload, 100% local, no account

JSON Formatter / Validator / Minifier

Paste or type your JSON. Format it with 2 or 4 spaces, minify it, or just validate. Everything stays in your browser.

How JSON Formatter works

JSON formatter, validator and minifier lets you paste raw JSON and instantly see whether it is valid, view it with readable indentation, or shrink it to the smallest possible single line for production payloads. The error messages pinpoint the exact location of syntax problems so you can fix them without guessing.

Formatting adds consistent indentation so the structure is readable at a glance, while minifying strips all whitespace for the smallest production payload. Validation covers structural syntax (missing commas, unclosed brackets, trailing commas, unquoted keys), not JSON Schema.

Frequently asked questions

Is the JSON text I paste sent anywhere?

No. Parsing, validation and formatting all run in your browser using the built-in JavaScript JSON engine. The text you paste stays on your device and is never transmitted to Sunasty or any third party.

What is the difference between "format" and "minify"?

Formatting adds consistent indentation and newlines so humans can read the structure at a glance. Minifying strips all whitespace to produce the smallest possible string, useful for reducing payload size in HTTP responses or config files.

Can it catch all JSON syntax errors?

It catches every syntax error that the JSON specification defines: missing commas, unclosed brackets, trailing commas, unquoted keys, and so on. It does not validate against a schema (JSON Schema), only structural syntax.

Does it work offline?

Yes, once the page has loaded. Because the processing happens on your device, you can disconnect from the network and the tool keeps working. This is the clearest proof that your data never leaves your machine.

Is it free? Do I need an account?

It is completely free and requires no sign-up. There are no watermarks, no daily limits and no tracking cookies needed to use the tool.