Beautify, minify and validate JSON in your browser, with parse errors reported at the exact line and column. A structure summary shows the top-level type, how many keys the document contains, how deeply it nests, and its size in bytes.

How to use it

  • Paste JSON into the input area.
  • Choose Beautify for indented, readable output, or Minify to strip every unnecessary byte.
  • If parsing fails, read the reported line and column and look at that exact spot.
  • Check the summary for a quick sense of the document shape before you start reading it.

What the strict grammar forbids

JSON is far stricter than the JavaScript object literals it resembles, and almost every parse failure comes from the same handful of habits. Keys must be double-quoted strings; bare identifiers are not permitted. Single quotes are never valid for strings. A trailing comma after the final element of an array or object is a syntax error, even though editors and linters have trained you to add them. Comments do not exist in JSON at all. Numbers cannot have a leading zero, a leading plus, or a trailing decimal point, and the special values NaN, Infinity and undefined are not part of the grammar.

Strings must be valid Unicode with control characters escaped, so a literal newline inside quotes is invalid and must be written \n. Because the tool reports the precise line and column where the parser gave up, the usual workflow is to jump there and look immediately before the marker, since a missing comma is detected only when the next token arrives.

Why the structure summary helps

Depth and key count tell you quickly whether an API response is a flat record or a deeply nested tree, which is exactly what you need to know before writing a parser or a JSONPath expression. Byte size matters for payload budgets: minifying removes whitespace only and never alters values, so it is always safe to send the minified form. Beautifying is purely cosmetic in the other direction. Everything runs locally in your browser, so API responses containing tokens or personal data are never uploaded anywhere.

Frequently asked questions

Does minifying change my data?

No. It removes insignificant whitespace between tokens. Key order, values, types and escaping are untouched, and the minified document parses to exactly the same structure.

Why is my large integer coming back slightly wrong?

JSON numbers are parsed as IEEE 754 doubles, which represent integers exactly only up to 2 to the power 53 minus one. Identifiers such as Twitter-style snowflake IDs exceed that and lose precision. The standard fix is to transmit such values as strings.

Is my JSON uploaded for validation?

It is not. Parsing and formatting are done by your browser own JSON engine inside the page, so nothing is sent to a server.

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