generate json schema from json
Paste one or more JSON documents and pick JSON Schema to get a draft 2020-12 schema with type, required, format and $defs.
All fields are required.
nick is missing from the second item: not in required.
type becomes an array containing "null".
uuid, email and date-time recognized.
Requires Detect tuples; items: false closes the array.
A field is optional when it is missing from at least one of the objects observed at that position, whether in different documents or in different items of the same array. If every object in a 50-item array has the key phone, it is required; if one does not, it becomes phone?: string. A null value does not make the field optional: it makes it nullable (string | null). The two concepts are different in APIs and in languages, so the tool keeps them apart. The All fields optional switch marks every field optional, which is useful for PATCH bodies and partial responses.
A JSON Schema is a language-independent JSON document that a validator (such as Ajv, in JavaScript) uses at runtime. A TypeScript type exists only at compile time. To validate in TypeScript with the same type, use the Zod target.
Because they were missing from at least one sample. required lists only the keys present in every object observed at that position. Use more samples to refine it, or All fields optional to require none.
An array becomes type: array with items describing the elements, already merged from all samples. Empty arrays generate items: {}, which accepts any value. With Detect tuples on, fixed-length arrays with different types use prefixItems.
Yes. Paste one document after the other, or an array with all of them. The tool merges the samples: missing fields become optional, null makes the field nullable, and different types become anyOf.
export type Root = RootItem[];
export interface RootItem {
id: number;
number: string;
status: string;
createdAt: string;
total: number;
customer: Customer;
items: Item[];
tags: string[];
shipping: Shipping;
billing?: Shipping;
couponCode?: string;
}
export interface Customer {
id: string;
name: string;
email: string;
phone: string | null;
}
export interface Item {
sku: string;
name: string;
qty: number;
price: number;
}
export interface Shipping {
street: string;
city: string;
zip: string;
}
A string with a few repeated values, in at least 8 samples, becomes an enum.
Date-time, date, UUID, email, URL and IPv4.
Objects with the same fields become one type.
Keys that look like ids or dates become a map, and an empty object becomes a map of unknown values.
A fixed-length array with different types per position, like ["a", 1].
Avoids int when the samples happen to contain only integers.
Rejects trailing commas, comments, single quotes and similar.
Language style: camelCase, snake_case or PascalCase, annotated with the original key. Dataclass and TypedDict always keep the keys.
Go, C#, Java, Swift and Pydantic. In other languages the field stays a string.
readonly in TypeScript, frozen in Python, init in C# classes and let in Swift.
The JSON is processed in your browser. Nothing you paste or open is sent to servers.