RAML vs. OAS: Which Is the Best API Specification for Your Project?

Designing and documenting APIs well is essential to working on API projects. APIs should be easy to use, understand, and maintain. Ensure your API design is clearly and effectively communicated to your users and teammates. You need to generate the entirety of your API design, together with documentation, code, assessments, mocks, and so forth. What is the excellent way to do all that? An API specification language is one way to do that. An API spec language is a way of writing down your API design using a general layout that humans and machines can read. It lets you write your API layout in a simple and structured manner, which you may use to create all varieties of awesome things. There are many API spec languages. However, the popular ones are RAML and OAS. RAML stands for RESTful API Modeling Language, and it's a language that uses YAML to put into writing your APIs. OAS stands for OpenAPI Specification, a language that uses JSON or YAML to write down your APIs. In this post, I will evaluate RAML and OAS and tell you what they can do for you.

Features

RAML and OAS have some standard features. They both:

• Support RESTful APIs, which are a way of making APIs that follow some rules and conventions for how they work on the web.
• Let you write the resources, methods, parameters, headers, responses, schemas, examples, security schemes, and more of your APIs.
• Let you reuse stuff across your APIs, like data types, traits, resource types, parameters, responses, etc., which you can write once and use many times.
• Let you split your API spec into multiple files and import them using references or includes.
• Let you check your API spec for errors and make sure it follows the language rules.
• Let you make docs for your APIs from your API spec that your users can see and try.

But RAML and OAS also have some differences. For example:

• RAML uses YAML as its format, while OAS uses JSON or YAML. YAML is shorter and friendlier to look at than JSON, but JSON is more common and supported by more tools and platforms.
• RAML has annotations, which are extra things that you can add to any part of your API spec. Annotations can give you more info or data about your APIs that the language doesn't cover. For example, you can use annotations to mark some parts as old or new. OAS doesn't have annotations by itself,

Benefits

RAML and OAS can both help you with your API design in different ways. They both:

• Help you make consistent APIs and follow RESTful APIs' best practices and conventions.
• Help you share your API design with your users and teammates.
• Help you make all kinds of cool things from your API specs, like docs, code, tests, mocks, etc., which can save you time and hassle.
• Help you work with different tools and platforms that support the language rules, like editors, frameworks, libraries, etc., which can make your work easier and better.

But RAML and OAS also have some unique benefits that make them stand out from each other.

 For example:

• RAML is more expressive and flexible than OAS. It lets you write your APIs more naturally and easily, using features like annotations, overlays, extensions, libraries, etc. It also lets you customize your API spec to fit your needs and style.
• OAS is more interoperable and compatible than RAML. It lets you write your APIs in a more universal and standard way, using features like OpenAPI extensions, callbacks, links, etc. It also enables you to use the OpenAPI ecosystem, which has a significant and active community of developers, vendors, tools, etc.

Drawbacks

RAML and OAS also have some disadvantages to your API design. They both:

• They need some learning and skill to use them well. You must know RESTful APIs' language format, rules, concepts, and principles.
• It may cover only some situations you want to express or document for your APIs. You may need other tools or methods to complete your API spec.
• API development or consumption may only be compatible with specific tools or platforms. You may need converters or adapters to switch between different languages or formats.

But RAML and OAS also have some specific drawbacks that make them less attractive than each other. For example:

• RAML is less popular and mature than OAS. It has a smaller and less active community of developers, vendors, tools, etc., which may limit its growth and improvement. It also has fewer features and options than OAS, mainly for security and linking.
• OAS is more complex and lengthy than RAML. It has more extensive and more diverse language rules, which may make it harder to read and write. It also has more features and options than RAML,

Use Cases

Depending on your goals and preferences, you can use RAML and OAS for different API projects. They both:

• It can be used for any type of RESTful API, whether public or private, simple or complex, internal or external, etc.
• It can be used for any stage of the API lifecycle, whether it's design, development, testing, deployment, management, etc.
• It can be used for any API team size, whether solo or collaborative, small or large, local or remote, etc.

But RAML and OAS also have some specific use cases that make them more suitable than each other for particular scenarios. For example:

• RAML is more suitable for API projects that require more creativity and flexibility. For example, we can use RAML for experimental, innovative, or customized APIs. We can also use RAML for APIs focusing more on the user experience and the business logic than technical details.
• OAS is more suitable for API projects that require more interoperability and compatibility. We can also use it for standard, stable, or compliant APIs. We can also use it for APIs that focus more on the technical details and the integration than on the user experience and the business logic.

Which one do I opt for, RAML or OAS? Well, to be honest, I like both. Both have strengths and weaknesses and can help me with my API layout in exceptional methods. But if I had to choose one, I could go with RAML. Why? Because RAML is fun and less complicated to use than OAS. RAML lets me write my APIs simple manner and expressively use YAML and annotations. I also like how RAML allows me to personalize my APIs to fit my needs and style, using overlays, extensions, libraries, etc. Don't get me wrong: OAS is extraordinary too. I appreciate how OAS lets me write my APIs in a universal and standard way, using JSON or YAML and OpenAPI extensions. I also understand how OAS allows me to use the OpenAPI ecosystem, which has a lot of excellent tools and resources.

But sometimes, I find OAS too complex and lengthy for my taste. OAS makes me write too much code and details for my APIs. OAS also limits my creativity and flexibility for my APIs.

Of course, this is just my view. You may have a different perspective based on your experience and use cases. The best API spec language is the one that works best for you.

Conclusion

I compared RAML and OAS as two popular API spec languages in this post. Then, I showed you what they can do for you regarding the features and benefits of your API design.