How to use this tool
How to check JSON
Paste your text. The preview displays Valid JSON when parsing succeeds and shows an error when it fails. JSON Lines is also detected, so a valid JSONL result does not mean the entire input is a single JSON document.
Common syntax errors
JSON uses double quotes for object keys and strings. Remove trailing commas and comments; use true, false and null in lowercase. For example, {"active":true} is valid, while {"active":true,} is not.
Syntax is not schema validation
This tool checks parsing, not a JSON Schema or business rules. Error wording comes from the browser, and the reported location may be approximate. A syntactically valid document can still have missing application fields.
Input and output example
The first example has a trailing comma. Remove it to produce valid JSON.
No sign-up required. JSON content is processed locally.