Codegen

April 21, 2026 · View on GitHub

jsonschema codegen <schema.json|.yaml> --target/-t <target> [--name/-n <name>]
  [--json/-j] [--verbose/-v] [--debug/-g]
  [--resolve/-r <schemas-or-directories>]
  [--default-dialect/-d <uri>]

JSON Schema is a declarative language for defining the structure of JSON data. The JSON Schema CLI offers a codegen command that generates type definitions from a JSON Schema, allowing you to use the schema as a source of truth for your application's data types.

This command is experimental. We are actively working on this functionality and things might break or change without notice. We are actively seeking feedback to make this better. Please open an issue at https://github.com/sourcemeta/jsonschema/issues with any problems you find.

Warning

This command currently only supports JSON Schema 2020-12 and TypeScript as a target language. We will extend support to other programming languages and dialects once we make the foundations stable.

Keyword Support

Not every JSON Schema keyword maps directly to type system constructs. This implementation aims to provide complete structural typing, and you are expected to use a JSON Schema validator at runtime to enforce remaining constraints.

Vocabulary	Keyword	TypeScript
Core (2020-12)	`$schema`	Yes
Core (2020-12)	`$id`	Yes
Core (2020-12)	`$ref`	Yes
Core (2020-12)	`$defs`	Yes
Core (2020-12)	`$anchor`	Yes
Core (2020-12)	`$dynamicAnchor`	Yes
Core (2020-12)	`$dynamicRef`	Yes
Core (2020-12)	`$vocabulary`	Ignored
Core (2020-12)	`$comment`	Ignored
Applicator (2020-12)	`properties`	Yes
Applicator (2020-12)	`additionalProperties`	Partial (language limitations)
Applicator (2020-12)	`items`	Yes
Applicator (2020-12)	`prefixItems`	Yes
Applicator (2020-12)	`anyOf`	Yes
Applicator (2020-12)	`patternProperties`	Partial (language limitations)
Applicator (2020-12)	`propertyNames`	Ignored
Applicator (2020-12)	`dependentSchemas`	Pending
Applicator (2020-12)	`contains`	Ignored
Applicator (2020-12)	`allOf`	Yes
Applicator (2020-12)	`oneOf`	Partial (language limitations)
Applicator (2020-12)	`not`	Cannot support
Applicator (2020-12)	`if`	Partial (language limitations)
Applicator (2020-12)	`then`	Partial (language limitations)
Applicator (2020-12)	`else`	Partial (language limitations)
Validation (2020-12)	`type`	Yes
Validation (2020-12)	`enum`	Yes
Validation (2020-12)	`required`	Yes
Validation (2020-12)	`const`	Yes
Validation (2020-12)	`minLength`	Ignored
Validation (2020-12)	`maxLength`	Ignored
Validation (2020-12)	`pattern`	Ignored
Validation (2020-12)	`minimum`	Ignored
Validation (2020-12)	`maximum`	Ignored
Validation (2020-12)	`exclusiveMinimum`	Ignored
Validation (2020-12)	`exclusiveMaximum`	Ignored
Validation (2020-12)	`multipleOf`	Ignored
Validation (2020-12)	`minProperties`	Ignored
Validation (2020-12)	`maxProperties`	Ignored
Validation (2020-12)	`dependentRequired`	Pending
Validation (2020-12)	`minItems`	Ignored
Validation (2020-12)	`maxItems`	Ignored
Validation (2020-12)	`minContains`	Ignored
Validation (2020-12)	`maxContains`	Ignored
Validation (2020-12)	`uniqueItems`	Ignored
Unevaluated (2020-12)	`unevaluatedItems`	Pending
Unevaluated (2020-12)	`unevaluatedProperties`	Pending
Meta-Data (2020-12)	`title`	Ignored
Meta-Data (2020-12)	`description`	Ignored
Meta-Data (2020-12)	`default`	Ignored
Meta-Data (2020-12)	`deprecated`	Ignored
Meta-Data (2020-12)	`examples`	Ignored
Meta-Data (2020-12)	`readOnly`	Ignored
Meta-Data (2020-12)	`writeOnly`	Ignored
Format Annotation (2020-12)	`format`	Ignored
Format Assertion (2020-12)	`format`	Ignored
Content (2020-12)	`contentEncoding`	Ignored
Content (2020-12)	`contentMediaType`	Ignored
Content (2020-12)	`contentSchema`	Ignored

Examples

For example, consider the following schema that describes a person:

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "type": "object",
  "properties": {
    "name": { "type": "string" },
    "age": { "type": "integer" }
  },
  "required": [ "name" ]
}

The codegen command will generate the following TypeScript types:

export type PersonName = string;

export type PersonAge = number;

export interface Person {
  "name": PersonName;
  "age"?: PersonAge;
  [key: string]: unknown | undefined;
}

Generate TypeScript types from a JSON Schema

jsonschema codegen path/to/my/schema.json --target typescript

Generate TypeScript types with a custom type name prefix

By default, generated types use Schema as the prefix. You can specify a custom prefix using the --name/-n option:

jsonschema codegen path/to/my/schema.json --target typescript --name Person

Output the generated code as JSON

jsonschema codegen path/to/my/schema.json --target typescript --json