How to use JSON Schema
- 1. Paste an instance. The JSON you want to check.
- 2. Paste a schema or infer one. Inference is a starting point, not a contract.
- 3. Read errors. Ajv instancePath plus message.
- 4. Tighten required fields. Arrays of objects are the best signal.
About this tool
JSON Schema is how APIs document payloads without inventing a custom IDL. Validation in the browser means a fixture never leaves your machine. Inference from one sample will over-fit — treat it as a draft.
Draft and strictness
Ajv runs in non-strict mode so common 2020-12 / draft-07 schemas still load. Formats like email need extra plugins and are not all wired here.
Inference limits
A single object marks every key required. Paste an array of production-shaped objects before you trust optionality.
Code examples
Schema
{ "type": "object", "required": ["id"] }