Open API Generator
Generate clients, servers, and docs from OpenAPI specs for 40+ languages.
Open the official app on openapi-generator.tech
This tool is hosted by its maintainers. Click below to open openapi-generator.tech in a new tab — it's their official demo.
Browse developer tools →What's next with Open API Generator?
Choose how you want to get started.
Use it free
Open the official tool or demo — no account needed.
Self-host it
Run the open-source version on your own infrastructure.
What is Open API Generator?
OpenAPI Generator is an open-source tool that automates the creation of API client libraries, server stubs, documentation, and configuration files using the OpenAPI Specification (OAS). It streamlines development by eliminating the need for manual code writing, allowing developers to focus on core functionality. The tool is widely used by API maintainers, backend developers, and DevOps teams to accelerate integration and maintain consistency across systems. Its primary purpose is to reduce repetitive coding tasks, ensuring that APIs can be rapidly prototyped, documented, and consumed by diverse platforms and languages. By leveraging OAS, it addresses the challenge of maintaining compatibility between API definitions and implementation code, particularly in environments where multiple teams or technologies are involved.
How it works
OpenAPI Generator is a command-line tool and web interface that transforms OpenAPI specifications (in YAML or JSON) into executable code. It enables developers to generate client SDKs, server frameworks, and documentation for REST APIs, ensuring alignment between the API definition and its implementation. The tool is designed to solve the problem of repetitive code generation, such as writing boilerplate for HTTP requests, error handling, and data serialization. It supports 50+ client generators for languages like Python, Java, and JavaScript, as well as server stubs for 40+ technologies, including Java and Go. OpenAPI Generator excels at producing client libraries for API consumption, with customizable templates using Mustache syntax. It also generates server-side code stubs, enabling rapid development of backend services. Specialized generators create database schemas (e.g., MySQL) and GraphQL schemas, expanding its utility beyond standard API implementations.
How to use it
- 1Prepare an OpenAPI specification file (YAML/JSON) defining the API endpoints, parameters, and responses. 2. Choose a generator for clients or servers, specifying the target language or framework. 3. Customize templates or configure options like API base URL and authentication methods. 4. Execute the generator to produce code, which can be integrated into projects or distributed as SDKs. Practical tips include using the CLI for automation, validating the OpenAPI spec with a validator tool, and leveraging pre-built templates for common frameworks like Spring Boot or FastAPI.
What it can do
- API code generation
Use cases
Assumptions and limitations
Assumptions
- source: https://github.com/OpenAPITools/openapi-generator
- license: Apache-2.0 — free to use
- privacy: Self-hosted — you control your data
Limitations
- Limited support for newer OpenAPI v3.1 features in some generators
- Customization requires familiarity with Mustache templating syntax
- Some advanced server-side features (e.g., complex DI containers) may need manual adjustments
- Dependent on the accuracy and completeness of the input OpenAPI spec
- Smaller communities for niche language generators compared to mainstream ones
Understanding the result
Generate clients, servers, and docs from OpenAPI specs for 40+ languages.
Tool details
- Clearly flagged when a network request is needed.
- No account, no sign-up, and no tracking of your content.
- Powered by (Apache-2.0).
- Built with
- (OpenAPITools/openapi-generator)
- License
- Apache-2.0
- Runs locally
- No — requires a network request
- Verification
- Not yet verified
- Input
- Query
- Output
- Text
Built with OpenAPITools/openapi-generator. OpenToolVault provides the discovery and browser interface while crediting the original project maintainers.
- Built with
- License
- Apache-2.0
Open-source project
OpenToolVault is an independent directory. We are not affiliated with or endorsed by this project.
References
- / — GitHub Repository
Upstream project · GitHub
- Apache-2.0 License
Upstream project
Frequently asked
What is OpenAPI Generator used for?
OpenAPI Generator is used to automate the creation of API client libraries, server stubs, documentation, and configuration files from an OpenAPI specification. It enables developers to generate code for multiple languages and frameworks, reducing manual coding efforts and ensuring consistency between API definitions and implementations.
How does OpenAPI Generator work?
The tool processes an OpenAPI specification (YAML/JSON) and uses predefined or user-customized templates to generate code. It parses the spec to extract endpoints, parameters, and response structures, then applies templating logic to produce language-specific code. For servers, it generates boilerplate for frameworks like Spring Boot or FastAPI, while clients are built for platforms like Python or JavaScript.
How do I generate a Python client for an API?
1. Save your OpenAPI spec as `api.yaml`. 2. Run `openapi-generator generate -i api.yaml -g python -o ./output`. 3. The tool will create a Python package with client classes for each endpoint. 4. Install the package via pip and use it to make API calls, handling authentication and request/response parsing automatically.
How does OpenAPI Generator compare to Swagger Codegen?
OpenAPI Generator is an evolution of Swagger Codegen, with improved support for OpenAPI v3 and more generators. While Swagger Codegen focuses primarily on client SDKs, OpenAPI Generator also supports server stubs, database schemas, and GraphQL. It has a larger community and more active maintenance, though some legacy Swagger features may be deprecated.
How do I fix an error about missing dependencies?
If the generator complains about missing dependencies, ensure all required libraries are installed. For example, Python clients may require `pip install openapi-generator` and `pip install requests`. For Java, check if Maven or Gradle dependencies are properly configured. Verify the OpenAPI spec syntax using a validator tool to avoid parsing errors.