JSON to JSON Schema converter
Turn sample JSON into a JSON Schema: this JSON to JSON Schema generator detects formats like email, date-time and UUID, and merges arrays of objects into one item schema.
What you get
- A JSON Schema generator for draft 2020-12 or draft-07, with types, required fields and formats (email, date-time, uuid…) detected.
- Checked with Ajv: your JSON always validates against the schema.
- Create JSON Schema from JSON in one paste, or from many samples at once, so optional fields are found.
- Private and free: everything runs in your browser, nothing is uploaded, and there is no sign-up.
How each result is checked
- The generated schema is compiled with Ajv, the most widely used JSON Schema validator.
- Your sample is validated against the generated schema. It must pass.
What can't convert exactly
- A schema inferred from one sample can only describe what the sample shows. Review required fields and enums before relying on it.
- Turn on "Top-level array = list of samples" to infer one schema from many records.
Questions
Which draft is used?
Draft 2020-12 by default. Draft-07 is available in the options.
Are optional fields detected?
Yes, when you provide several samples: keys that are missing in some records are not required.
How do I generate JSON Schema from JSON?
Paste a sample of your JSON. You get a JSON Schema (2020-12 or draft-07) with types, required fields and formats, and Ajv checks that your JSON validates against it.
Can I generate one schema from multiple samples?
Yes. Paste a JSON array of samples and turn on "Top-level array = list of samples": the schema covers all of them, and fields missing from some samples become optional.
How do I use the generated schema?
Validate data with any JSON Schema library: in JavaScript, compile it with Ajv; in Python, use the jsonschema package. Editors such as VS Code also use it for autocompletion through the "$schema" key or their settings.
How do I convert JSON to JSON Schema online?
Paste your JSON or open a file on the left (or click Example). The JSON Schema appears on the right as you type, already checked. Copy it, or download it as a file. Nothing is uploaded.
Can the JSON Schema output be wrong?
Every result is checked before it is shown (the checks are listed on this page). If a check fails, the page says "Review needed" and why, instead of presenting the output as correct, and anything that cannot convert exactly is named in the notes.