Question 1

What's the most common JSON error?

Accepted Answer

Trailing commas after the last item in an array or object. JavaScript lets you get away with it; strict JSON does not. A close second is single quotes — JSON requires double quotes around keys and string values, no exceptions. If your file was hand-edited, one of these two is almost always the culprit.

Question 2

Can it validate a JSON Schema?

Accepted Answer

No — this tool only checks syntax. That's the 'is this even parseable' step. If you need to validate that your JSON matches a specific shape (required fields, correct types, nested structure), you need a JSON Schema validator, which is a separate tool.

Question 3

Is there a size limit?

Accepted Answer

Files up to around 1 MB are fine. Bigger than that and your browser starts feeling it — since validation is done locally, performance depends on your machine. For massive files, validate representative chunks instead of the whole blob.

Question 4

Why does my JSON parse in one tool but not another?

Accepted Answer

Some tools are lenient and silently accept things like trailing commas, comments, or unquoted keys (sometimes called JSON5). Standard JSON is stricter. If the source is a config file or a copy-pasted snippet, it may have gone through a lenient parser first — clean it up before trusting it elsewhere.

Question 5

Is my data uploaded?

Accepted Answer

No. Validation runs in your browser. Whether your JSON is an API response with user data or a secret config file, nothing gets sent to our servers — safe to paste sensitive payloads.

JSON Validator

What is JSON Validator?

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