Paste JSON + Schema — instant validation. Uses ajv (110M downloads/week, embedded).
User: {"type":"object","properties":{"name":{"type":"string"},"email":{"type":"string","format":"email"},"age":{"type":"number","minimum":0}},"required":["name","email"]}
Product: {"type":"object","properties":{"id":{"type":"number"},"price":{"type":"number","minimum":0}},"required":["id","price"]}
Array: {"type":"array","items":{"type":"string"},"minItems":1}