Paste JSON to pretty-print it with 2 spaces, 4 spaces or tabs, minify it, or sort its keys. Validation uses your browser's own JSON.parse (RFC 8259): invalid input shows the first error's exact line and column, valid input shows the key count and byte size. You can also drop in a file. Nothing leaves this tab.
Formatted JSON will appear here. Press Format, or Cmd / Ctrl + Enter.
Runs in this tab · nothing is uploaded · Verify in 10 seconds →
A JSON formatter pretty-prints compact or minified JSON, minifies it back, and reports syntax errors with a line and column. Use it for API payloads, config files and copy-paste blobs that need to be readable. Some people call the same thing a JSON beautifier, or say they want to prettify JSON; whatever the name, it is one operation: parse, then re-serialize with indentation.
Paste JSON, drop a .json file, or load the sample. Format rewrites with the indent you pick: 2 spaces (default), 4 spaces or tabs. Minify removes whitespace. Sort keys orders object keys alphabetically. The status bar shows the key count and UTF-8 byte size when the document is valid, or the exact line and column when it is not. Validation uses your browser's JSON.parse, no network request.
~/faq
No. Parsing, formatting and validation run in this tab with the browser's JSON.parse. LocalFirstTools has no upload endpoint; the text you paste is never sent.
The status bar points at the line and column of the first syntax problem, a trailing comma, a missing quote, or a comment. JSON does not allow comments or trailing commas; remove them and format again.
Format (pretty-print) adds indentation and line breaks so people can read the document. Minify emits a single compact line, which is smaller to copy into logs or requests.
Standard JSON cannot contain comments. If your file uses // or /* */ it is JSONC, not JSON. Strip comments first, then format.
Paste the JSON into the input pane and press Format (or Cmd/Ctrl + Enter). Pick 2 spaces, 4 spaces or tabs in the Indent selector first; 2 spaces is the default and matches what jq and Prettier emit.
None. Formatter, beautifier, prettifier and pretty-printer are different names for the same operation: parse the text, then write it back with indentation and one key per line. The values are untouched.
Yes. Open your browser's developer tools, switch to the Network tab and press Format: no request carries the text. Parsing, formatting and validation are plain JavaScript running in this tab.
Chosen for the same job, not just the same category.