Question 1

Why does it say my JSON is invalid when it looks fine?

Accepted Answer

The usual causes are a trailing comma after the last item, single quotes instead of double quotes around keys or strings, or an unescaped newline inside a string. Validate reports the line and column of the first thing it could not parse, so start there.

Question 2

Is my JSON sent to a server?

Accepted Answer

No. The parsing and formatting are done by your browser’s own JSON engine, in the page. That matters here more than on most tools, because config files and API responses routinely carry passwords, keys and personal data.

Question 3

Can formatting change my JSON?

Accepted Answer

A little, because the JSON is parsed and written out again. Integers with more digits than a JavaScript number can hold — 64-bit database keys, Discord and Twitter ids — come back rounded, so 12345678901234567890 becomes 12345678901234567000; formatting names any value that did, and quoting it in the source keeps it exact. Numbers are also written in their shortest form (1.50 becomes 1.5), \u escapes come back as the characters they stand for, a key that appears twice keeps only its last value, and keys that look like whole numbers move to the front of their object.

Question 4

What does sorting keys do to arrays?

Accepted Answer

Nothing. Array order is meaningful in JSON, so it is left exactly as it was. Only the keys inside objects are reordered, at every level of nesting.

Question 5

Is there a size limit?

Accepted Answer

None imposed by the tool. It is working in your browser’s memory, so the practical ceiling is your own machine - a few megabytes of JSON is unremarkable, a few hundred will be slow.

Free JSON formatter and validator

Report a problem