JSON can be perfectly valid syntax and still be wrong for your application — a required field missing, a number sent as a string, an unexpected extra property. That's the gap JSON Schema is built to close.

What JSON Schema actually checks

• Whether required fields are present
• Whether each field's data type matches expectations (string, number, boolean, array)
• Whether values fall within allowed ranges, patterns, or enumerated options

Syntax validation vs schema validation

Basic syntax validation only confirms your JSON is well-formed, parseable text. Schema validation goes a level deeper, confirming the data itself matches the contract your application expects — the two are complementary, not interchangeable.

Start with the basics first

Before reaching for a full schema validation library, make sure your JSON is syntactically valid in the first place using a straightforward formatter and validator — it's the fastest way to rule out a simple typo before debugging a more complex schema mismatch.