Format, minify or validate JSON in your browser. Preserve number spellings, string escapes and key order, with syntax error locations and a notice for repeated object keys.
Need several developer steps together? Open Developer Studio →
Your JSON is processed entirely in your browser without uploads, accounts, dependencies or saved input history. Formatting changes only whitespace outside string tokens, so numbers and escaped strings stay as written. The original remains available for review and no JSON content is executed.
Yes. Numbers are treated as source tokens, not converted into JavaScript Number values. Large integers, negative zero, decimal trailing zeros and exponent spellings are kept exactly as written. String escape spellings and object member order are also retained. This is a whitespace formatter rather than a JSON.parse/JSON.stringify round trip or canonical JSON generator.
Repeated member names are accepted by the syntax checker, preserved in output and counted in a notice. Keys are compared after JSON escape decoding, within each individual object. Other programs may reject duplicates or keep only one value; resolve repeated keys deliberately before sharing JSON. No keys are sorted or merged.
Strict JSON values: objects, arrays, strings, numbers, booleans and null, including top-level primitives. Comments, trailing commas, single-quoted strings, unquoted keys, undefined, NaN and Infinity are rejected. This tool does not validate JSON Schema, application rules, security, numeric interoperability or the content of strings.
Validate only checks syntax and shows statistics, with no output or export. Format and Minify perform the same syntax check before generating output. Errors show a one-based line and UTF-16 column, plus a zero-based UTF-16 position. An error location indicates where parsing failed; the cause may be earlier. Browser textareas normalize pasted line endings to LF.
Input is limited to 200,000 UTF-16 units, 50,000 tokens and 100 nested containers. Formatted output is limited to 1,000,000 units; deeply indented input may require Minify instead. Over-limit runs return no partial output. A leading BOM is rejected rather than silently removed. Raw unpaired UTF-16 surrogates are rejected to avoid replacement on UTF-8 download; JSON backslash-u escapes remain preserved, including escaped surrogate units.
No. Processing stays on your device, with no network requests or saved input history. Copy and JSON download include only the output. Clear keeps your current action and indentation; Try an example restores Format with two spaces. Editing input or controls invalidates previous results. Third-party consumers may still interpret accepted number ranges and duplicate members differently.
