What is the difference between JSON validation and formatting?

Validation checks that JSON follows the specification (valid syntax). Formatting only changes whitespace and indentation for readability. You can format valid JSON and also validate it separately.

What common JSON mistakes does this catch?

Trailing commas, single-quoted strings, unquoted keys, missing colons, mismatched brackets and braces, and control characters in strings.

Does it validate against a JSON Schema?

This tool validates JSON syntax. For schema validation (checking that values match a defined structure), use a dedicated JSON Schema validator.

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Invalid JSON is one of the most common sources of bugs in API integrations, configuration pipelines, and data processing scripts. A single misplaced comma, an unquoted key, or an extra bracket can break an entire system — and the error messages from programming languages are often cryptic and hard to locate. devtoolkit.sh's JSON Validator cuts through the confusion. Paste your JSON and the validator checks it against the full JSON specification in real time, reporting not just whether it is valid but exactly where the problem is, with a line number and character offset. It catches all common mistakes: trailing commas, single-quoted strings, missing commas between elements, unescaped control characters in strings, and mismatched brackets. Valid JSON is confirmed with a clear success indicator and the tool also reports the number of keys and nesting depth, giving you a quick overview of the document structure. Everything runs in your browser — no API calls, no data retention, no usage limits.

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FAQ

What is the difference between JSON validation and formatting?: Validation checks that JSON follows the specification (valid syntax). Formatting only changes whitespace and indentation for readability. You can format valid JSON and also validate it separately.
What common JSON mistakes does this catch?: Trailing commas, single-quoted strings, unquoted keys, missing colons, mismatched brackets and braces, and control characters in strings.
Does it validate against a JSON Schema?: This tool validates JSON syntax. For schema validation (checking that values match a defined structure), use a dedicated JSON Schema validator.