OpenAPI vs RAML: What are the differences?

Introduction: OpenAPI and RAML are two popular languages used in API documentation. Although both serve a similar purpose, there are some key differences between the two.

1. Format: OpenAPI uses YAML or JSON for specifying the API, while RAML uses YAML or JSON plus an XML extension for describing the API. This difference in formats allows for slightly different ways of organizing and presenting the API documentation.

2. Version Control: OpenAPI has a long history and has evolved through multiple versions, with the latest being OpenAPI 3.0. RAML, on the other hand, had a major release in 2013 and is currently in version 1.0. This difference in versioning can affect the availability and maturity of certain features in each language.

3. Tooling Ecosystem: OpenAPI has a more extensive tooling ecosystem compared to RAML. This includes a wide range of tools for generating server stubs, client libraries, and documentation from the OpenAPI specifications. RAML's tooling ecosystem, while not as extensive, still provides tools for various tasks but may have fewer options available.

4. Schema Definition: OpenAPI uses JSON Schema for describing and validating data models, while RAML uses a built-in schema definition language called JSON Type Language (JTL). This difference in schema definition can affect how data models are defined and used in the API documentation.

5. Maturity and Adoption: OpenAPI has a larger community and wider adoption compared to RAML. This means that OpenAPI specifications are more commonly used and supported by API developers, tooling providers, and API consumers. RAML, while still widely used, may have a slightly smaller community and fewer resources available.

6. Extensibility: OpenAPI offers a more extensible framework for adding custom specifications and annotations through the use of extensions. RAML, while also supporting extensibility, may have more limited options for adding custom specifications in certain areas.

In summary, OpenAPI and RAML differ in their formats, version control, tooling ecosystem, schema definition, maturity, and extensibility. While OpenAPI has a larger community and more extensive tooling support, RAML offers a different approach to API documentation and may still be a viable option depending on specific requirements and preferences.