Result Waiting for input
Paste JSON. Broken input is fine — try
Format, validate, and minify JSON. Errors name the exact character that broke, and pasted Python dicts convert in one click.
Four things break JSON constantly, and none of them look wrong at a glance. A comma before a
closing brace or bracket is legal in JavaScript and never in JSON. Strings must use double
quotes, so 'single' fails. Object keys must be quoted too, so
{name: "x"} fails. And JSON has no comments, which is why a file copied out
of tsconfig.json will not parse.
All four are detected here by name, with the exact character marked.
Printing a dictionary in Python gives you single quotes and True,
False, None where JSON wants true, false,
null. Paste one and the repair button converts it. It uses the parser rather
than find-and-replace, so an apostrophe inside a string survives.
JSON puts no limit on how big a number can be, but JavaScript reads every number as a 64-bit float, so anything above about 9 quadrillion loses its last digits. If you work with Snowflake IDs or large database keys, a formatter can quietly change them. This one re-emits the digits exactly as written.
{"id": 1, "id": 2} is valid JSON, and every parser silently keeps only the
last value. That is data loss inside a document that looks fine, so it is flagged here rather
than passed over.
Log exports and streaming APIs usually emit one JSON object per line, which is NDJSON rather than a single document. Paste several and you will be offered a one-click wrap into an array.
Keys stay in the order you wrote them, including keys that look like numbers — a plain JavaScript object would reorder those. Turn on sort keys when you want a canonical order, for example before diffing two documents.
The parser runs on your machine. Nothing is sent anywhere, including tokens inside the JSON.