JSON Validator – Check Your JSON and Find the Error

Paste your JSON

Checks standard JSON (RFC 8259). The wording of the error comes from your browser, so it can differ slightly between Chrome, Firefox and Safari.

What does a JSON validator do?

JSON is strict. One missing quote, one stray comma or a comment is enough to make a parser reject the whole document. A validator checks the text against the JSON rules and, when it fails, shows where. This one gives the line and column, a small excerpt with a marker under the problem, and a list of the usual causes it can spot in your text.

How to use it

Paste your JSON into the box.
Press Validate. A valid document shows its type, size and nesting depth.
If it is invalid, read the line and column, then check the likely causes list.

The most common JSON mistakes

{ "a": 1, }          trailing comma
{ 'a': 1 }           single quotes
{ a: 1 }             key without quotes
{ "a": 1 // note }   comment
{ "a": undefined }   value JSON does not have
{ "a": True }        should be true

Frequently asked questions

Why is my JSON invalid when it works in JavaScript?

A JavaScript object literal is more forgiving than JSON. It allows single quotes, unquoted keys, trailing commas and comments. JSON allows none of those.

Does the order of keys matter?

Not for validity. Duplicate keys are allowed by the parser but usually mean a mistake, and most parsers keep only the last one.

Is a bare string or number valid JSON?

Yes. Modern JSON allows any value at the top level, such as "hello", 42 or null, not only objects and arrays.

Why does the error message look different in another browser?

Each browser words parser errors its own way. The line and column are worked out from whatever position the browser reports.

Is my JSON uploaded?

No. Validation runs in your browser, so private data stays on your device.

Results are estimates for information only and are not financial, tax or legal advice.