The State of API Directory and Marketplaces in 2021

In 2015, IBM estimated the API Economy to reach $2.2 Trillion by 2018¹. Everyone at that time expected an Open API Economy disrupting the digital world and ushering in a new marketplace like open source. The OpenAPI initiative was also founded around this time.

Fast forward to the present, and it seems like the cloud, with a market sizing of about $370 Billion², has stolen the thunder of the Open API Economy! APIs are the backbone of all applications. To review the API Economy’s state, we took a deep dive into the popular API directories, marketplaces, and cloud providers to understand how this vision for an API marketplace is progressing.

The State of API Directory and Marketplaces in 2021 across ProgrammableWeb, RapidAPI, Azure, AWS and Google
  1. There are numerous API platforms based on specific products, SaaS, information exchanges, and others. There are even more tools and sandboxes. For this analysis, we restricted our focus to the cross-platform, general-purpose APIs, and functions. We picked a combination of simple directories, API marketplaces, and hyper-scale cloud providers’ API exchanges. ProgrammableWeb, RapidAPI, Microsoft Azure, Amazon Web Services (AWS), and Google Cloud Platform (GCP) made the top 5 in this area.
  2. With almost 24,000 APIs listed, ProgrammableWeb is the largest directory of APIs³. ProgrammableWeb was acquired by MuleSoft in 2013 and primarily focuses on information resources on APIs and developer aids for enabling APIs. Next, as a dedicated marketplace of APIs comes in RapidAPI. It supports over 20,000 APIs⁴. Both provide a list of APIs available for developers across free public APIs and different paid tiers. While RapidAPI enables you to run the APIs, ProgrammableWeb is only a directory listing service.
  3. The sum of all application and data-focused APIs of the Top 3 Cloud providers is less than half of ProgrammableWeb or RapidAPI listings. But this area is fast growing. Azure lists about 7,000 APIs⁵, AWS lists about 4,500 APIs⁶, while GCP hosts less than 1,000 APIs⁷.
  4. Information services are the most popular APIs, with categories like Weather, Mapping, Social, Transportation, and Datasets leading the rankings. This shows the open API economy’s bias towards lower-risk use cases vs. business transactions being supported in the platform-specific marketplaces.

Salesforce’s $6.5 Billion acquisition of Mulesoft and Visa’s $5.3 Billion acquisition of Plaid reinforce API’s potential as the principal digital integrator. But there is a significant opportunity in developing federated API marketplaces hosting millions of developer APIs. Given the hyper-scale cloud providers’ investment appetite and the need for sticky and differentiated services, an application-focused API marketplace can be the answer.

Happy Reuse!


While every effort has been made to provide accurate and updated information, we regret any omission or error.








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