JSON Formatter
Format, validate and minify JSON locally. Keep every number exact.
INPUT
0 charactersOUTPUT
Awaiting inputYour JSON, with room to breathe.
Format for readability. Minify for compact output. Values stay exactly as written.
Exact number spelling, key order and string escapes are preserved. No repair or key sorting. Long lines scroll within each editor. Limits: 1 MiB UTF-8 input, 100 nesting levels, 4 MiB output.
Enable JavaScript to format JSON locally. No server submission is available.
Make JSON easier to work with.
- Paste JSON, or load the synthetic sample.
- Choose indentation and select Format JSON. Use Minify for compact output.
- Copy the complete result or download devxtools.json.
Format and minify both validate strict JSON. They change whitespace outside strings, preserving number spelling, string escapes, property order and duplicate entries. No repair or automatic key sorting happens.
Your data stays here.
Processing runs in a local Web Worker. Input and output are never uploaded, logged, saved in browser storage or included in URLs. Reset and leaving the page clear this workspace. Copy and Download are deliberate local actions.
Small details, kept intact.
Large integers, exponent notation and negative zero are preserved without a JavaScript number round-trip. Duplicate keys stay in the result with a warning because other parsers may keep only the last value. Escaped Unicode code units are preserved; raw unpaired surrogates are rejected to avoid changing them in a UTF-8 download.
Supports up to 1 MiB of UTF-8 input, 100 nesting levels and 4 MiB of output. Processing stops after 2 seconds. Large results show a bounded preview; Copy and Download always use the full result.
A few useful answers.
Why is my JSON invalid?
Check for trailing commas, missing commas or colons, unmatched brackets, and property names without double quotes. The tool reports the start of the token where parsing failed. Use “Go to location” to select that position; the actual mistake can be just before it.
Can JSON contain comments or single quotes?
No. Standard JSON requires double-quoted strings and property names, and does not allow comments. This formatter rejects them instead of silently repairing or removing content.
What is the difference between format and minify?
Formatting adds indentation and line breaks for reading. Minifying removes unnecessary whitespace for compact output. Spaces and escapes inside strings are preserved in both modes.
Will large numbers or duplicate keys change?
No. The original tokens are preserved. Even integers beyond JavaScript’s safe range and numbers such as 1e999 keep their exact spelling. Repeated decoded property names are reported without removing them; how another system interprets duplicates is outside the formatter’s control.
How are error columns counted?
Lines and columns are one-based. Columns count UTF-16 code units, matching browser text selection: a tab counts as one, and most emoji count as two. CRLF counts as one line break. String errors point to the string token’s start, not a guessed character inside it.
Is my JSON uploaded or saved?
No. The page and local processor load as normal website assets, but your JSON stays in browser memory. There is no share URL or cloud save. You can explicitly copy the result or save a local file.