Swagger/OpenAPI generation for TypeScript: best tools

Swagger/OpenAPI generation for TypeScript: Complete guide to tools

Developing modern web applications in TypeScript is inextricably linked to creating type-safe API clients. Manually writing interfaces for each endpoint is a time-consuming and error-prone task. Fortunately, there is a powerful approach — automatic generation of TypeScript code from OpenAPI (Swagger) specifications. In this article, we will take a detailed look at the best tools for this task, their capabilities, and usage examples.

Why use generation from OpenAPI?

OpenAPI (formerly Swagger) is a standard for describing REST APIs. Using a YAML or JSON specification file, you get:

• 100% typing — TypeScript interfaces that exactly match the request and response schemas
• Backend synchronization — when the API changes, just regenerate the code
• Reduced errors — the TypeScript compiler catches type mismatches at development time
• IDE autocompletion — IntelliSense suggests fields and types

Top tools for generating TypeScript from OpenAPI

1. openapi-typescript-codegen (recommended)

This tool has gained popularity due to its simplicity and modern approach. It generates clean, well-structured code with support for axios or fetch.

Installation:

npm install -D openapi-typescript-codegen

Usage example:

npx openapi-typescript-codegen --input ./spec.yaml --output ./generated --client axios

Generated code:

// generated/models/User.tsexport interface User {    id: number;    name: string;    email: string;    role: 'admin' | 'user';}

// generated/services/UserService.tsexport class UserService {    public async getUsers(): Promise<User[]> {        return this.httpRequest.request({            method: 'GET',            url: '/users',        });    }}

Advantages:

• Support for OpenAPI 3.0 and 3.1
• Generation of models, services, and types for requests
• Optional generation of hooks for React Query
• Customizable templates via Handlebars

2. OpenAPI Generator (openapi-generator)

The official generator from the OpenAPI community. Supports over 50 languages, including TypeScript (multiple generators).

Installation:

npm install -D @openapitools/openapi-generator-cli

Usage example:

npx openapi-generator-cli generate \    -i spec.yaml \    -g typescript-axios \    -o ./generated

Generated code:

// generated/api.tsexport const UsersApiAxiosParamCreator = {    getUsers: async (options?: AxiosRequestConfig): Promise<RequestArgs> => {        const localVarPath = `/users`;        return {            url: localVarPath,            method: 'GET',        };    }}

Features:

• Generators: typescript-axios, typescript-fetch, typescript-angular
• Authorization support (OAuth2, API Key)
• Generation of documentation and tests
• Works via CLI or Maven/Gradle plugins

3. swagger-typescript-api

A lightweight and fast generator focused on clean TypeScript without unnecessary dependencies.

Installation:

npm install -D swagger-typescript-api

Usage example:

npx swagger-typescript-api -p ./spec.yaml -o ./generated -n api.ts

Generated