API Blueprint provides a markdown format for describing your APIs and is backed by Apiary with a strong open source community and a few projects for API documentation and mocking.
Mashery IO Docs
Built by Mashery (Intel), IO Docs are designed to provide an interactive console/ documentation for users to view your API and try making test calls. However, outside of the console, IO Docs are very limited and I have not been able to find many projects based around it.
RAML is backed by several industry leaders and provides a human and machine readable format (YAML) for defining APIs, as well as a strong open source community and freely hosted API designers, mocking service, API Console, and API Notebook allowing even more ways for developers to explore and use your API.
One of the original specs, Swagger has recently been upgraded to allow for development in either a YAML or JSON format and brings with it a large open source community and tools for designing, mocking, and documenting your API.
The original RESTful API definition language, WADL is based on WSDL and defines the API in an XML format. Support for WADL has greatly decreased due to the emergence of Swagger, RAML, and API Blueprint.
Apigility is the leading RESTful API Development framework in PHP, built by Zend Technologies it provides an easy to use interface for defining your APIs but does not take advantage of spec imports at this time.
Based on the Rails framework, Rails API is an API framework for Ruby.
Grape provides an alternative framework for API development in Ruby and is designed to work with Swagger.
Jersey is a popular Java Framework for building APIs with JAX-RS.
MuleSoft’s Anypoint Platform for APIs provides several free API tools including a visual API designer to help you build your RAML spec, a Swagger importer, and a markdown powered API Portal generator to let you build your own custom API portal with API Console and unlimited API Notebooks. However, to use their API Management tools you must pay for the service, but there is no lock-in and no requirement that you do so when using the other tools.
Mashape likewise offers a free API design tool and portal for sharing your API. Listed on their site, Mashape also offers a free API portal that provides an interactive console, API documentation, and most notably- multiple code snippets to help developers get started quickly. Mashape also offers free API Management (proxy) for up to 12,500 requests per day, and allows you to monetize your API for a 20% cut.
3Scale offers a powerful, free API Manager (proxy) that let’s you take advantage of up to 500 developers in your API making up to 50,000 API calls a day.
More known as an integration platform, WS02 has also developed an open source API Manager. Unfortunately, I haven’t had the chance to try this out yet.
Layer 7/ CA
Recently acquired by CA, Layer 7 is a leader in API Management and is rated most highly by Forrester Wave.
SOA has surprised many with its API Management suite and quickly become a leader in enterprise API management.
Perhaps the most vocal of all API Providers, Apigee is known for its dynamic solution, but has been plagued by complaints of slowness. They are, however, without doubt still a leader in the space. However, they are also among the more expensive of the solutions.
IBM provides an intuitive API Manager that plays well with its other technologies already known in the enterprise space.
Recently acquired by Intel, Mashery has prided itself on an intuitive, easy to use interface, their IO Docs, and their ability to market and communicate on behalf of their clients. The biggest downside to Mashery is that they are currently the most expensive solution on the market (compared to those reviewed by Forrester).
Known for their integration platform, Tibco likewise provides an API Management platform. However, it appears as if Tibco has been plagued by financial problems and the company recently removed themselves from the public market.
Another integration platform company, MuleSoft has taken great strides since the 2014 Q3 Forrester Wave review which tested their first version of their system. The new version of their API Manager surpasses the one reviewed by Forrester in every way and is designed to bridge the worlds of SOA and APIs while offering a large array of capabilities at low cost.
3Scale struggled in the Forrester Wave, but strives to provide one of the lowest-cost, yet powerful platforms for API Management.
Microsoft/ Windows Azure is surprisingly a late comer to the API Management game, however backed by the Azure cloud and with an intuitive interface, my guess is they would have faired quite well in reviews.
Still looking into Mashape’s paid solution.
APIMatic.io provides a free service for auto-generating SDKs in multiple languages including Java, PHP, Ruby, Android, Windows, and Node.js. It supports API Blueprint, Swagger, RAML, IO Docs, and Google Discovery, and also lists available SDKs in its searchable directory.
REST Unite, currently in beta provides a free service for generating SDKs in PHP, Ruby, Python, ActionScript, C#, Objective-C, Scala, and Java. It currently supports Postman, Alpaca, Swagger, and IO Docs. REST United also provides a developer portal with documentation and SDK code snippets.
The Rest API Tutorial is a creative commons project with videos and documentation on what REST is, its constraints, and how to design and build your RESTful API.
MuleSoft’s API Best Practices
This 8 part series on MuleSoft’s blog provides an overview of key best practices including design, spec driven development, nouns, CRUD, Content-type, hypermedia, HTTP responses and status codes, error messages, versioning, and use of an API Management System.
Building Your API for Longevity
Mike Stowe’s 45 minute presentation on Building Your API for Longevity incorporates several important and key practices for ensuring a long lived API. Given at RubyConf 2014.
REST API Best Practices
Mike Stowe’s 20 minute presentation on “18 best practices” you should incorporate when building your API, as given at API Strategy & Design Conference in 2014.
by D. Keith Casey Jr. & James Higginbotham
Still under development, the API Design Book highlights key areas of concern while developing an API while also showcasing best practices.
RESTful Web APIs
by Leonard Richardson & Mike Amundsen
An in-depth book taking a look at RESTful Web APIs and Design
by Michael Stowe
Undisturbed REST covers API design and best practices while taking advantage of modern techniques and tooling.
MuleSoft API Training
MuleSoft offers a nice 8 hour overview training of API Design and RAML.
If you’re into APIs, and need a good laugh – this collection of gifs will brighten your day.