JSON Validator

Validate JSON syntax and get clear, descriptive error messages

What is it and how does it work?

A JSON validator checks whether a block of text is valid JSON and, when it is not, tells you exactly where and why it breaks. JSON has strict syntax rules — double quotes around every key and string, no trailing commas, no comments — and a single violation makes the entire document unparseable. A validator runs the same parse a program would and surfaces the first error with its location, turning a cryptic "unexpected token" into a precise pointer at the character that needs fixing.

Most JSON errors come from a handful of habits carried over from JavaScript or hand-editing: single quotes instead of double, a comma left after the last item, keys without quotes, or a missing closing bracket. Catching these before the data reaches an API, config loader or import step saves the frustrating round-trip of a server rejecting the payload with a vague message. This tool validates entirely in your browser, so you can check sensitive configuration or payloads without sending them anywhere.

Common use cases

• Fixing a config file: validate a settings.json or package manifest to find the exact line a trailing comma or missing brace is breaking.
• Checking an API payload: confirm a request body is valid JSON before sending it, so you debug your data rather than the endpoint.
• Cleaning pasted data: validate JSON copied from logs or a chat to spot where it was truncated or malformed.

Frequently asked questions

What are the most common JSON syntax errors?

Trailing commas after the last element, single quotes instead of double quotes, keys without quotes, and unclosed brackets or braces. JSON is stricter than JavaScript object syntax, so habits from writing JS code are the usual culprits.

Why is my JSON valid in JavaScript but not here?

JavaScript object literals allow single quotes, unquoted keys, trailing commas and comments; JSON allows none of these. Code that works in a JS file can still be invalid JSON, which is exactly the kind of mismatch a validator catches.

Does validating check my data against a schema?

No — this checks syntactic validity: whether the text is well-formed JSON that parses. Confirming that values match expected types or required fields is schema validation, a separate step performed against a JSON Schema.

Can I include comments in JSON?

Standard JSON does not allow comments, so adding them makes a document invalid. Some tools accept comment-friendly supersets like JSONC, but for portable, spec-compliant JSON you must remove comments before validating.

JSON

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