JSON Validator
Checks your JSON as you type. Valid documents get a summary of their shape; broken ones get the line, the column and a pointer to the character.
Valid JSON ·
Reading the error message
Browsers word JSON errors differently, but they all describe the first character the parser could not accept. “Unexpected token }” usually means a trailing comma before a closing brace. “Unexpected end of JSON input” means a bracket or quote was never closed. “Expected property name” means a key without double quotes.
When the file is valid, the summary tells you whether the top level is an object or an array, how many keys it holds and how deeply it is nested — a quick way to confirm an API returned what you expected. To reformat it, switch to the JSON formatter.
Questions people ask
Which JSON standard does this validator check against?
It uses the browser’s native JSON.parse, which implements ECMA-404 / RFC 8259. If it passes here, it will parse in every standards-compliant JSON library.
Does it validate against a JSON Schema?
No. This checks syntax: whether the text is well-formed JSON. Checking that the data has the right fields and types is schema validation, a separate step done with a JSON Schema library in your code.
Can it accept comments or trailing commas (JSON5, JSONC)?
No, by design. Those formats are not JSON, and a file with comments will fail in most APIs. Use “Fix it with AI” to strip them and convert the file to plain JSON.
Why is the reported column slightly off?
The parser reports where it gave up, which is sometimes just after the real mistake. For a missing comma, the error points at the start of the next value. Look at the line shown and the one above it.