Readable data, precise feedback
JSON Formatter & Validator
Turn a dense JSON file into something you can read. Format or minify it, find syntax errors, and review duplicate keys while keeping every value intact.
Start with your JSON
Make the structure clear.
Keep the meaning intact
Change the layout, keep the values.
Format adds indentation and line breaks between values. Minify removes that extra whitespace. Both preserve the original number spelling, member order, string escapes and duplicate members, without rounding large integers or reordering keys.
Validation follows JSON syntax. A top-level string, number, boolean or null is allowed, as well as an object or array. Comments, single-quoted strings, trailing commas, NaN and Infinity are not accepted. Errors include a line and column so you can find the problem.
Duplicate keys and unpaired Unicode escapes receive compatibility warnings. Applications may keep different values for duplicate keys or handle those Unicode values differently. Syntax validation does not verify a JSON Schema, business rules or a receiving application’s numeric range.
Processing stays in this browser tab. Input is not uploaded or saved by the tool. Limits are 2 MiB of UTF-8 input, 128 nested containers, 200,000 syntax tokens, 100,000 values and 8 MiB of output. The first 100 compatibility warnings are shown. A leading UTF-8 byte order mark is removed with a notice.
Starting with a spreadsheet export? Use the CSV Cleaner & Converter to create JSON from a table.