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Test codecov npm version

Extended version of

Inspired by YousefED/typescript-json-schema. Here's the differences list:

  • this implementation avoids the use of typeChecker.getTypeAtLocation() (so probably it keeps correct type aliases)
  • processing AST and formatting JSON schema have been split into two independent steps
  • not exported types, interfaces, enums are not exposed in the definitions section in the JSON schema


This project is made possible by a community of contributors. We welcome contributions of any kind (issues, code, documentation, examples, tests,...). Please read our code of conduct.

CLI Usage

npm install --save ts-json-schema-generator
./node_modules/.bin/ts-json-schema-generator --path 'my/project/**.*.ts' --type 'My.Type.Full.Name'

Note that different platforms (e.g. Windows) may different path separators so you may have to adjust the command above.

Programmatic Usage

// main.js

const tsj = require("ts-json-schema-generator");
const fs = require("fs");

const config = {
    path: "path/to/source/file",
    tsconfig: "path/to/tsconfig.json",
    type: "*", // Or <type-name> if you want to generate schema for that one type only

const output_path = "path/to/output/file";

const schema = tsj.createGenerator(config).createSchema(config.type);
const schemaString = JSON.stringify(schema, null, 2);
fs.writeFile(output_path, schemaString, (err) => {
    if (err) throw err;

Run the schema generator via node main.js.

Custom formatting

Extending the built-in formatting is possible by creating a custom formatter and adding it to the main formatter:

  1. First we create a formatter, in this case for formatting function types:
// my-function-formatter.ts
import { BaseType, Definition, FunctionType, SubTypeFormatter } from "ts-json-schema-generator";

export class MyFunctionTypeFormatter implements SubTypeFormatter {
    public supportsType(type: FunctionType): boolean {
        return type instanceof FunctionType;

    public getDefinition(_type: FunctionType): Definition {
        // Return a custom schema for the function property.
        return {
            type: "object",
            properties: {
                isFunction: {
                    type: "boolean",
                    const: true,

    public getChildren(_type: FunctionType): BaseType[] {
        return [];
  1. Then we add the formatter as a child to the core formatter using the augmentation callback:
import { createProgram, createParser, SchemaGenerator, createFormatter } from "ts-json-schema-generator";
import { MyFunctionTypeFormatter } from "./my-function-formatter.ts";
import fs from "fs";

const config = {
    path: "path/to/source/file",
    tsconfig: "path/to/tsconfig.json",
    type: "*", // Or <type-name> if you want to generate schema for that one type only

// We configure the formatter an add our custom formatter to it.
const formatter = createFormatter(config, (fmt) => {
    fmt.addTypeFormatter(new MyFunctionTypeFormatter());

const program = createProgram(config);
const parser = createParser(program, config);
const generator = new SchemaGenerator(program, parser, formatter, config);
const schema = generator.createSchema(config.type);

const schemaString = JSON.stringify(schema, null, 2);
fs.writeFile(output_path, schemaString, (err) => {
    if (err) throw err;


-p, --path 'index.ts'
    The path to the TypeScript source file. If this is not provided, the type will be searched in the project specified in the `.tsconfig`.

-t, --type 'My.Type.Full.Name'
    The type the generated schema will represent. If omitted, the generated schema will contain all
    types found in the files matching path. The same is true if '*' is specified.

-i, --id 'generatedSchemaId'
    The `$id` of the generated schema. If omitted, there will be no `$id`.

-e, --expose <all|none|export>
    all: Create shared $ref definitions for all types.
    none: Do not create shared $ref definitions.
    export (default): Create shared $ref definitions only for exported types (not tagged as `@internal`).

-f, --tsconfig 'my/project/tsconfig.json'
    Use a custom tsconfig file for processing typescript (see instead of the default:
        "compilerOptions": {
            "noEmit": true,
            "emitDecoratorMetadata": true,
            "experimentalDecorators": true,
            "target": "ES5",
            "module": "CommonJS",
            "strictNullChecks": false,

-j, --jsDoc <extended|none|basic>
    none: Do not use JsDoc annotations.
    basic: Read JsDoc annotations to provide schema properties.
    extended (default): Also read @nullable, and @asType annotations.

    Do not sort properties.

    Do not allow additional items on tuples.

    Do not create a top-level $ref definition.

    Skip type checks for better performance.

    Do not encode references. According to the standard, references must be valid URIs but some tools do not support encoded references.

    Provide additional validation keywords to include.

-o, --out
    Specify the output file path. Without this option, the generator logs the response in the console.

--additional-properties <true|false>
    Controls whether or not to allow additional properties for objects that have no index signature.

    true: Additional properties are allowed
    false (default): Additional properties are not allowed

Current state

  • interface types
  • enum types
  • union, tuple, type[] types
  • Date, RegExp types
  • string, boolean, number types
  • "value", 123, true, false, null, undefined literals
  • type aliases
  • generics
  • typeof
  • keyof
  • conditional types

Run locally

yarn --silent run run --path 'test/valid-data/type-mapped-array/*.ts' --type 'MyObject'


yarn --silent run debug --path 'test/valid-data/type-mapped-array/*.ts' --type 'MyObject'

And connect via the debugger protocol.

AST Explorer is amazing for developers of this tool!

Debug Vega-Lite

To debug Vega-Lite's schema generation, you can clone Vega-Lite in the same directory as this library and run yarn run debug -f ../vega-lite/tsconfig.json -p ../vega-lite/src/index.ts -t TopLevelSpec --no-type-check.


To publish a new version, run the workflow at