Format, validate and minify JSON

JSON supports objects, arrays, quoted strings, numbers, true, false and null. Property names and strings require double quotes. Comments, trailing commas, single-quoted strings, JavaScript expressions and JSON5 extensions are rejected. Syntax checking does not validate a JSON Schema or confirm that the data is correct for your application.

Formatting adds line breaks and two spaces for each nested level; minifying removes whitespace outside strings. For example, an array containing 1, 2 and 3 keeps those three values in the same order in either mode. Spaces and escape sequences inside a quoted string remain exactly as entered. Objects and empty arrays stay compact when empty.

After bounded syntax validation, this tool formats the original tokens rather than serializing the parsed object. A numeric literal such as 9007199254740993 or 1.2300e+20 stays unchanged. Member order and repeated property names are retained. Duplicate names are still an interoperability risk: other software may keep only the last occurrence, reject them or behave differently. Retaining their spelling does not make duplicates safe for every application.

Line and column numbers identify where the strict parser detects an unexpected token; columns count UTF-16 code units, so some characters occupy two positions. An unfinished object can be reported at the end of the input. The preview is capped at 12,000 characters; Copy and Download JSON include the full result. Token, depth and UTF-8 output-byte limits prevent excessive allocations. No content is silently repaired.