Check whether a piece of JSON is valid, and find out exactly where it goes wrong if it is not. Your file never leaves this page. Everything happens in your browser, and there is no upload endpoint to send it to — that is checked by a build gate that fails if any network code reaches a tool’s bundle.
How to do it
- Paste the JSON you want checked.
- Read the verdict. If it is invalid, the position of the problem is given.
- Fix it and check again.
Questions
What counts as invalid JSON?
The specification is stricter than most people expect. Comments are not allowed. Trailing commas are not allowed. Keys must be in double quotes, and so must strings — single quotes are not JSON. NaN and Infinity are not JSON numbers.
Does it validate against a schema?
No. This checks that the document is well-formed JSON, which is a different question from whether it matches a schema your application expects.
Why does my configuration file fail?
Many tools accept a relaxed dialect — JSON with comments, or JSON5 — in their configuration files. Those are not JSON, and a strict parser is right to reject them.
Is anything I paste kept?
No. It is checked in your browser and nothing is stored.