Today, we have an application to handle almost everything that we do. All these applications use different APIs (Applications Programming Interfaces) to function. This means that developers need the best API directories to discover new functionalities easily and fast.

The APIs they find should not only be accurate but also up-to-date. The functionalities that they provide should do what they promise to do. The APIs, on the other hand, should be updated regularly to fix bugs and conform to changing technological advancements.

These APIs can only be found in the best API directories. If you are an API provider or developer, chances are that you have heard about Rapid or ProgrammableWeb. These are some of the best API directories we have today.

However, there are many other directories that you need to look at to discover new functionalities. We will discuss some of the best API directories for developers and API providers in this article.

Discover new functionalities with these API directories

GitHub Repository’s Public APIs

GitHub offers a repository of free APIs for use in software and web development. It is one of the best API directories for those looking for free APIs. The repository offers publicly available and open-source APIs organized by category.

Github’s API directory stands out from its competitors due to its API update process. If, for instance, an API you have implemented in your application is updated, you can simply update the same in your application using Git.

If you are a developer, you have used GitHub at one point in your career. You understand how thorough and organized the organization is. This means that even though you will be getting public and free APIs, you can be assured of getting something that has been tried and tested. 

If you are an API provider, ensure that you have followed their submission guidelines before submitting your API. was started by Ivan Goncharov with the aim of creating a REST API Wikipedia. He seems to have succeeded since the site currently has 2,368 APIs. The site uses unique criteria to curate the APIs that will get listed, making it one of the best API directories.

Some of the things they do before listing an API include;

  • Fixing mistakes. More than half of the specifications always have some mistakes.
  • Ensures that all formats are converted to OpenAPI 2.0.
  • Eliminates non-reliable and private APIs.
  • Ensures that specifications are updated daily.
  • Adds more data, such as categories and logos, among others.

The platform also offers an API of its own. This way, you can discover new functionalities in your own terminal or application without accessing a web browser. If you are an API provider, getting your API listed in is also easy. All you need to do is understand their criteria and meet their requirements.


Customers, partners, and development teams can discover new functionalities and connect to APIs from the single API directory or platform provided by Rapid. It is one of the most popular API directories with almost an API for every other functionality you might need.

Rapid provides a slick and clean interface, something that gives the directory an edge over its competitors. In addition, it allows developers to test APIs from the directory. This means that you do not have to set your own test environment for the APIs you want.

You can also categorize, organize, and track your APIs from the directory. However, a bigger percentage of APIs on Rapid are monetized. This might be a disadvantage for developers working under strict budgets.

Adding an API for API providers is also not difficult. According to a Rapid developer survey and insights (2019 – 2020), more than one million developers are using the directory to discover new functionalities, connect, and test APIs. This means that it is one of the best API directories for API providers, especially because of the traffic it generates.


Apart from being among the best API directories we have today, ProgrammableWeb is also the largest. However, this can be both an advantage and a disadvantage to developers. If you search a large box, you will likely find things that do not meet your requirements.

ProgrammableWeb was launched in 2005 and has always ensured that developers can understand APIs and discover new functionalities for their applications. However, you should ensure that you have tested their APIs before using them.

This is because some of the API listings in this directory are not up-to-date. Some of their APIs are also platform-specific while others are not free. If you are not sure about the APIs you get here, you are better placed to try other repositories. ProgrammableWeb has more than 24,000 APIs.

Unfortunately, the company has announced that it will be shutting down its operations after 17 years. This might not be the best directory for new API providers looking for the best API directory.

Even though some people might argue that does not qualify to be listed among the best API directories, it is the best platform for those who want to mess around. Here, you will find different APIs for your projects and experiments.

This directory has been classified as the best place for those looking for unique and quirky APIs for their projects. For instance, you are likely going to find the best API for dog facts, funny TV shows, or foodies in the API directory.

If you have developed an API that you think is funny or helps programmers discover new and funny functionalities, then is the API directory for you. Adding your APIs to this directory is easy. All you need to do is fill out their submission form and wait for a response.

Google APIs Explorer

Google APIs Explorer is different from all other API directories in this article. This is because you can only find public APIs developed by Google in this directory. Currently, you can find hundreds of Google’s public APIs here.

This directory is only suitable for developers who want to discover new functionalities offered by Google’s APIs. It is the best place for Google APIs, even though you can find some of these APIs in the other directories discussed in this article.

API3 Alliance

If, for instance, you are using technology to help recruiters in the healthcare industry, you understand the role played by APIs. They are the standard you need in all situations, especially when updating and normalizing your data stream.

Things can get out of hand for those working with blockchain applications. This is because these apps are different from others. So, which API directory is best suited for developers building blockchain applications?

The best API directory, also the largest, for developers looking to discover new functionalities that are blockchain compatible is API3 Alliance. The directory uses the Airnode module to avail APIs to the Web3 technology. Adding your APIs to API3 Alliance is not difficult, but you will have to answer a couple of questions.


M30 is one of the best API directories for micro APIs. These are APIs you can use as microservices. Amazon Web Services (AWS) offers some of the best services to developers and API providers. However, this comes at some cost, something that might be a challenge to developers operating under strict budgets.

Fortunately, you can get similar services with the M30 API directory. They offer a listing of proprietary and public APIs. The platform is well organized, efficient, and clean, giving it an edge over some of its competitors.

Postman API Network

Every developer who has ever used an API knows about Postman. Most developers have used its terminal at one point or another. However, it also provides a Graphical User Interface, the Postman API Network, for them to discover new functionalities. 

This directory comes with four different sections, making it one of the best API directories we have today. These sections include;

  • APIs
  • Workspaces
  • Collections
  • Teams

Apart from discovering new functionalities, you can also use the Postman API Network to find APIs that other developers are using. It provides Private and Public APIs sections to ensure that developers can use it for their own APIs as well.

The Workspaces and Teams sections is essential for software development company or developers who want to source development job leads or even network with other companies/developers. The Postman API Network is one of those directories every developer needs to know.


Rakuten is one of the most popular API directories and marketplaces. The platform makes marketing, selling, and managing APIs for developers easy. It also offers a simple and quick integration that developers can use to upload specifications and add parameters within no time.

Discovering new functionalities is also easy. You can start using the APIs you want fast. This is because you get all the documentation that you need to get started. You can also test the APIs in any browser of your choice.

If you are an API provider, you can list your APIs with Rakuten easily. It also handles things such as payment processing and billing for API providers. In addition, you can make as many API calls as you want without incurring extra costs.


Initially, APILayer was just a cloud-based API and SAAS provider. However, the company introduced an API directory and marketplace in 2022. Using this directory, API providers can easily make money using their APIs.

Currently, the directory is trusted by more than one million developers. You can find some of the most scalable and secure REST APIs in this directory. Unfortunately, they do not list free APIs. The only good thing is that you can get a free plan with all APIs without a credit card.

This directory is best suited for API providers and developers without budget restrictions. Providers benefit from money collection and key API management for all their listed APIs. All they need to do is to build their APIs and then let the directory handle everything else.

Zyla API Hub

Zyla API Hub is an amazing API directory, especially because it allows API providers to start earning from their APIs fast. In addition, the directory provides different levels of technical support depending on the requirements of API providers.

One of the things that make the Zyla API Hub stand out is its ability to allow API providers to change their trading approach. For instance, you can emphasize some functionalities or capabilities of your APIs.

You can also use the directory for sales promotion and to research how to improve the marketing of your APIs. Zyla API Hub makes it easy for API providers to monetize their APIs. Just like the APILayer directory, Zyla API Hub is best suited for API providers.


Apart from discovering new functionalities, the BuiltAPI directory is one of the best API directories that allows developers to network and build leads. APIs are grouped based on their vendors. You can find all APIs from the vendors beneath their names.

This directory is best known for offering PropTech APIs. These are APIs that provide built-world functionality. Using the BuiltAPI platform, you can get live demos in different languages. You can also test your APIs to ensure that they match your requirements.

The BuiltAPI directory provides examples of the look and feel of your API payloads. This is important in helping you understand how good the API will be when implemented in your applications.

Just like API3 Alliance, is one of the best API directories for developers working in blockchain technology. However, the directory is relatively new compared to most of the directories discussed in this article.

To get started with, you have to sign up for access. If you want to list your APIs with this directory, you should ensure that it is blockchain-enabled.

API Harmony

Built and owned by IBM, API Harmony is an API directory that developers can use to not only discover new functionalities but also find and use APIs in their applications. 

Instead of going through complicated information, API Harmony helps developers quickly understand an API and its intended use. It also provides them with information about supporting communities surrounding the APIs listed in the directory.

There are many API directories available to both developers and API providers. However, finding the best directory that can help you discover new functionalities is not easy.

You need to make sure that the directory you choose to use meets all your requirements. The directories discussed above are some of the best in the market today.