Frequently Asked Questions
Everything you need to know about JSON validation and json-validator.net.
What is JSON validation?
JSON validation is the process of checking whether a JSON string conforms to the JSON specification (RFC 8259). A valid JSON document has correctly matched braces, double-quoted keys and strings, no trailing commas, no comments, and valid value types.
Is this validator free?
Yes, completely free. No sign-up, no subscription, no rate limits. The tool is permanently free.
Is my JSON data safe?
Yes. All validation runs locally in your browser using JavaScript's built-in JSON.parse(). Your JSON is never sent to any server, never logged, and never stored.
Why do single quotes fail?
The JSON specification requires all strings (including object keys) to use double quotes. Single quotes are valid in JavaScript objects but not in JSON.
Why are trailing commas not allowed?
RFC 8259 explicitly disallows trailing commas. JavaScript allows them in objects and arrays, but JSON — as a language-neutral data interchange format — does not.
Can JSON have comments?
No. Standard JSON (RFC 8259) does not support comments of any kind. Remove // and /* */ comments before validating. If you need comments in config files, look into JSONC or JSON5.
What is the difference between JSON validation and JSON linting?
They mean the same thing: checking that a JSON string is syntactically correct. 'Linting' sometimes also implies style checking, but for JSON the primary concern is syntax validity.
Does it work on large files?
Yes. Since validation runs in your browser there are no server-imposed size limits. Very large files (100MB+) depend on your browser's available memory.
What JSON standard does this validator use?
RFC 8259, which is the current JSON specification. This is the standard used by all major programming language parsers and APIs.