JSON to JSON Schema
Generate a JSON Schema from a sample JSON document, with format detection, required fields and a choice of draft.
Every field present in the sample. Usually needs trimming afterwards.
date, date-time, email, uri, uuid, ipv4.
Keeps the sample value next to each field.
Files are processed in your browser and are never uploaded to a server.
How to use
Free to use with no sign-up, no install and no usage limit.
Paste a sample response and the schema appears as you type. Writing one by hand is fine for five fields and miserable for fifty, and the mistakes are always the same: a type copied from the field above it, or a field left out entirely.
Every item in an array is examined, not just the first. If one object in the list carries a field the others do not, that field still appears in the schema, and it is dropped from required because it demonstrably is not always there.
Mixed types inside an array become anyOf so that nothing is silently lost. Integers and decimals are the exception: they collapse to number, because splitting them into two branches makes the schema harder to read without making it more correct.
String formats are detected conservatively. Dates, timestamps, emails, URLs, UUIDs and IPv4 addresses are recognised in their unambiguous forms only. Guessing wrong here produces a schema that rejects real data, and that is harder to debug than a missing format.
What comes out is the shape of one example. Optional fields, value ranges and enumerations do not show up in a single sample, so treat the result as a first draft to edit rather than a finished contract.
Nothing is uploaded. API responses tend to contain real customer data, which is reason enough to keep this in the browser.