Say you’re creating an app that suggests movies and TV shows to watch while you’re waiting for a flight. Perhaps your plane arrives in half an hour, so the app recommends an episode of The Addams Family. Or, if your flight’s been delayed for several hours, perhaps a Ken Burns mini-series would be more fitting. That should be fairly simple to program, right? Well, there’s a strong chance it’s not.

For this app to be useful, first, you’d need a flight API to fetch flight arrival information. Then you’d need a media API that includes the runtime of each program. A developer may loop in many other APIs to refine the user experience, like APIs from popular streaming apps, auto-fill capabilities, or sentiment analysis.

As you can see, the apps we use every day involve many APIs in the background. And for developers, efficiently building an app means discovering the right APIs quickly and easily. These results need to be up-to-date and accurate, as well. API directories fill all these needs.

Many of us know about ProgrammableWeb and RapidAPI, but these only scratch the surface. There are many other helpful API directories for your development projects. Also, if you’re an API provider, you’ll want to list your API with as many of these API directories as you can to build your audience and spread your influence!

The 13 Best API Directories

1. APIs.guru

APIs.guru is an API directory with noble intentions. When Ivan Govcharov started the initiative, he wanted to create a Wikipedia for REST APIs.

Luckily, APIs.guru is as helpful in practice as it is in theory. The site lists 2,337 APIs at the time of writing, and it has criteria for curating what APIs are suitable for inclusion. APIs.guru assesses every submitted API to:

  • Filter out private and non-reliable APIs.
  • Convert different formats into OpenAPI(fka Swagger) 2.0
  • Fix mistakes; ~80% of specs have some
  • Add additional data, like logo, and categories.
  • Update specs daily

Even better, APIs.guru is available as an API in-and-of-itself. This means you can have a clear, well-organized list of up-to-date APIs delivered straight to your terminal, without even having to open a web browser.

If you maintain an API, it’s pretty simple to list your API with APIs.guru. You can read their criteria here. Make sure you match their requirements if you’re thinking of submitting your API, though, to make sure you qualify.

APIs.guru is the Wikipedia of APIs

The Wikipedia of APIs has its own API to boot!

2. Public APIs GitHub Repository

Public APIs’ GitHub repository is like APIs.guru’s older sibling. Like APIs.guru, Public APIs is a directory of public, open-source APIs that is clean, clear, and well-organized by category. It can also be updated without ever touching a search engine, as you can just update the directory using Git.

Public APIs is perhaps the best directory of open-source APIs on the internet, thanks largely to the thorough organization and a clear, modernist interface on their web properties like their homepage.

If you have a free, open-source API that you’d like included in the Public API GitHub repository, it’s simple to add. You can read their submission guidelines over here.

Public APIs Github repository and website

Public APIs provides a curated repository of high-quality, open APIs.

3. APIList.fun

If you’re ever looking for a list of APIs for experiments, projects, or just simply messing around, you should include APIList.fun on your bookmarks list. APIList.fun is the best source of quirky, unique APIs for all manner of projects.

If you’re looking for an API of Cat Facts (and, hey, who isn’t?) or an API for foodies, you’ll be able to find both and much more in this directory.

It’s also super simple to add your API!

API.list provides a quirky list of fun APIs for your project

API.list provides a quirky list of fun APIs for your project.

4. ProgrammableWeb

ProgrammableWeb is like the Best Buy of API directories. This is meant as both a recommendation as well as a warning. If you’ve spent much time wandering around in big box stores, you’ll know they tend to have a ton of stuff that might not be relevant to your needs.

While ProgrammableWeb, the first-ever API directory, is the largest one, not all of ProgrammableWeb’s API listings are kept up-to-date. There is a proliferation of paid and platform-specific APIs, as well, so you’d do well to look elsewhere if you’re looking for more open options.

That being said, the ProgrammableWeb directory is very comprehensive. It lists over 24,000 APIs at the time of writing. You can filter APIs by category, like Weather and Mapping, or rank them by popularity. If you want to see what’s out there, spend some time browsing ProgrammableWeb.

ProgrammableWeb is very much the name brand of API directories, and its site maintainers also publish helpful articles and cover new API releases. If you’re an API developer, you should absolutely list your API on this heavily trafficked API index!

ProgrammableWeb was the first ever API directory

ProgrammableWeb is the oldest and most comprehensive API directory, tracking 335 APIs just related to Weather.

5. RapidAPI Hub

RapidAPI is another heavy-hitter API directory. On the upside, it’s got many of the same strengths as ProgrammableWeb, but it’s also susceptible to many of the same shortcomings. Either way, it’s still worth a look if you’re searching for an API for a particular application.

A few details place RapidAPI over other API directories, large or small. A clean, slick interface is a strong selling point. The ability to test the APIs directly from the directory is the other unique aspect of RapidAPI that makes this API index notable. The ability to track, organize, and categorize the APIs you use is one final selling point.

RapidAPI Hub tends to attract monetized APIs, which could be a downside for developers on a budget. The strengths outweigh the weaknesses, though, by quite a large margin. You should have it in your link library for when you need to seek a new API.

If you manage an API, it’s easy to add your API, as well. A recent report found over one million developers use RapidAPI to find, test, and connect to APIs. Considering how much traffic RapidAPI generates, you’d be highly recommended to add your API here.

RapidAPI Hub API marketplace

The RapidAPI Hub is more of a marketplace, allowing developers to test APIs and enabling API owners to monetize their services.

6. M30

Do you need a reliable directory of micro APIs to serve as microservices? M30.com should be on your radar. M30 is intended to be an alternative to services from Amazon Web Services (AWS), and their listings of public and proprietary APIs is its nervous system.

The 50+ micro APIs mentioned in their GitHub repository and listed on M30.com aren’t merely useful for their platform, though. And even if you’re just looking for a general API directory, M30.com is still worth a look as it’s clean, efficient, and well-organized. It’s well worth a look and including it in your bookmarks of API lists!

You can also fill out this form for your API to be considered for inclusion at M30.com.

M30 is a curated list of simple programmable building blocks

M30 is a curated list of programmable building blocks.

7. API3 Alliance

APIs are the lifeblood of real-time data apps. As this continually updating data stream becomes increasingly normalized and mainstream, these resources become the standard for every situation. This can quickly become a logistical nightmare of file conversions, security and permissions issues, and more.

Things get particularly complex when dealing with blockchain, as it’s such a different paradigm altogether. So what are you to do if you need to integrate an API into a Web3 project?

API3 Alliance is the largest directory of API providers compatible with blockchain-based technology. These APIs are made available to Web3 technology via the clever Airnode module. Tools like the API3 Alliance bring us one step closer to blockchain becoming integrated into the fabric of our daily lives.

You can apply to have your API listed here.

API3 Alliance blockchain APIs

API3 Alliance houses a directory of blockchain-compatible Web3 APIs

8. Google API Explorer

This API directory breaks with the format of the rest on our list as it’s solely a directory of Google’s public APIs. There are hundreds of items on the Google API directory. It’s worth bookmarking for that reason alone — you don’t want to have to look up every single Google API you might need.

Google API Explorer

Google offers a searchable explorer of its public APIs.

9. Postman API Network

Postman has so many great things going for it. Although most of us are pretty used to the Terminal at this point, it’s still nice to have a GUI to browse and explore APIs. The Postman API Network is a major blessing for that reason alone.

The Postman API Network is divided into four sections: APIs, Collections, Workspaces, and Teams. Not only is the Postman API Network a wonderful way to discover new APIs, but it’s also an indispensable way to see what APIs others are using as well. The Postman API Network also has a section for both Public and Private APIs so that you can use it for your internal APIs too.

Thanks to the Teams and Workspaces sections, the Postman API Network could even be a useful tool for networking and sourcing leads for developer jobs. These features make the Postman API Network quite a helpful API directory.

Postman API Network

The Postman API Network boasts a wide range of functionality, in addition to being a solid way to discover APIs.

10. API.market

API.market is another API directory for APIs and blockchain technology. API.market seems to still be in the beta stages, although they offer a sign up for early access. It’s still worth a look for the listings of APIs coming soon, though! You’ll also be able to list your API (if it’s blockchain-enabled) if you get accepted into their early program.

API.market web3 APIs are coming soon

As of early 2022, most Web3 APIs on API.market are “Coming Soon.”

11. BuiltAPI

The BuiltAPI Marketplace is another API directory that could also serve as a good source for networking and developing leads. It’s organized by API vendor, with a list of their APIs beneath. The BuiltAPI API marketplace is also noteworthy for being dedicated to PropTech APIs that deliver functionality for the built world.

You can try out the API directly through the portal, with live demos in nearly any language you can think of. They also provide examples of what the API payload looks like, so you’ll get some idea of how useful an API might be ahead of time.

BuiltAPI API marketplace property management

The BuiltAPI Marketplace collates APIs for property and real estate management.

12. PromptAPI

PromptAPI is still relatively new and small, but still worth mentioning. Of note is that all of the APIs listed here have a free plan to help you test them out ahead of purchasing.

PromptAPI marketplace API directories

PromptAPI Marketplace lists a handful of helpful APIs with free plans.

13. Any API

Last but not least, we round out our list of API directories with Any-API.com. Any-API.com lists over 1400 public APIs as well as their documentation. It ranges from the world-famous to completely obscure, and all points in-between. Whether you’re looking for the New York Times’ Books API or a synonym finder, you’ll find it here! Any-API is powered by apilayer, LucyBot, and APIs.guru.

Any API directory

Any-API hosts documentation and test consoles for over 1400 public APIs.

Honorable Mentions

  • API Expert: A curated list of meaningful APIs that compares performances with links to developer docs and data.
  • Meta API: A nicely-designed catalog of 300+ public APIs.

API Directories: Final Thoughts

APIs are supposed to make us more productive, not give us more busywork to fill our already overflowing days. To truly make the most of APIs in your development projects, you need a source of high-quality, trustworthy, dependable APIs that are well-organized and easily searchable so you can find what you need when you need it.

As for API providers trying to market their service, they need all the traffic they can get. APIs are built to be used — that’s the main point. Getting your API listed with an API directory is a great way to gain traffic and build your reputation with minimal effort!

Did we forget an API directory? Please comment and link to it below, and we’ll consider adding it to this list!