How JSON Formatter & Validator works
JSON Formatter & Validator parses your input with the browser's native JSON.parse, catches any syntax error, and re-emits the result with the indent you pick (2 spaces, 4 spaces, or a tab) or as a single-line minified string. Validation errors include the line and column where parsing failed so you can jump straight to the problem.
How to use
Paste a JSON blob, paste an API response, or load sample data. Pick an indent style, and read the formatted output. To minify for production payloads, switch to minify mode and copy the result.
Frequently asked questions
Does JSON Formatter support JSON5, comments, or trailing commas?
No — only strict JSON (RFC 8259). Comments, trailing commas, single-quoted strings, and unquoted keys will be rejected. Use a JSON5-specific tool or preprocess the file if you need lenient parsing.
Is the parsed data ever sent to a server?
Never. Parsing and stringifying happen entirely in the browser. This is why the tool is safe to use on production configs, secrets, or PII.
Why does my minified string look different from the input?
Minify strips every character that is not required: whitespace, indentation, and unnecessary quoting differences get normalised. The semantic content is identical and round-trips through JSON.parse without changes.
What does "Error at line 12, column 4" actually point to?
It points to the position in your input string where the parser gave up. Line numbers start at 1, columns at 1. The caret in the error lets you jump visually to the broken token.
Can I format very large JSON documents?
Yes for files up to a few megabytes. Above that, the browser may slow down because the entire parsed object is held in memory. For huge documents, format on disk with `jq` or your editor.