How the check works
A JSON Schema is itself JSON that describes required keys, types, and constraints like minimum, pattern or enum. This tool compiles your schema with Ajv — the reference validator used by most JavaScript tooling — and runs it against your data client-side, supporting both the current draft 2020-12 and the still widely used draft-07 (detected from the schema’s $schema field).
Every failure lists the keyword that rejected it (required, type, pattern…), a plain message, the instancePath pointing at the value in your data, and the schemaPath pointing at the rule in the schema, so you can fix either side quickly.
No schema yet?
"Generate schema from this JSON" infers a basic schema from your sample data: object shapes with required keys, array item types, integer vs number, and a couple of common string formats (email, date-time). It is a starting point for hand-tuning, not a replacement for a schema you design deliberately.
Frequently asked questions
Which JSON Schema drafts are supported?
Draft 2020-12 (the current version) and draft-07 (still common in older tooling). The draft used is detected from the schema’s $schema keyword; if it is missing, 2020-12 rules are used.
What do instancePath and schemaPath mean?
instancePath is a JSON Pointer into your data (for example /total/amount) showing where the invalid value is. schemaPath is a JSON Pointer into the schema showing which rule failed (for example #/properties/total/properties/amount/minimum).
Does the generated schema include validation like minimum or pattern?
No — it infers types and required keys plus email/date-time string formats only. Add numeric ranges, regex patterns or enums by hand once you have the shape.
Is my data uploaded to check it?
No. Ajv runs entirely in your browser; the schema and data never leave your device.
Can I validate an array of records?
Yes — give the schema a top-level type: "array" with an items schema, and paste the array as your data.