How to Promote and Market your API: API Directories

What are API Directories? What are they useful for? What are the best options > out there?

Answers to all these and more are revealed below!

What are API Directories?

In my previous post on why you should create an OpenAPI spec for your API, I mentioned that many API directories will only index you if you have a spec, or they will surface the spec if you have one. However, I didn't explain what API directories were, so let's get to that.

API directories (also known as API indexes) are essentially lists of APIs that developers will find useful when solving certain problems. Imagine you needed an API for sending emails. Sure, you could just type that into Google - and you'll find options like SendGrid and Mailgun - but you might miss out on other APIs like Resend that are potentially more affordable or easier to use. These days, most established APIs have the resources to invest heavily in ads and SEO, while many startups do not - essentially leaving you with fewer options. API directories act as (sometimes) neutral platforms where all APIs get indexed, are discoverable, and are presented similarly.

Benefits of Using an API Directory

If you've followed this guide from part 1, you have your API developed using "Hype Tools", generated documentation from your OpenAPI, and are now ready to onboard users. Rather than going out and trying to find users, you can list your API on several API directories and have users come to you!

• You should list on as many directories as practical; most of them are free
• Being listed on multiple pages also has SEO benefits, with multiple pages referencing and linking to your API on popular domains
• Unlike API marketplaces, API directories do not typically act as a middleman between your users and your API - you keep 100% of your revenue and have a direct relationship with your user

Which API Directory Should I Pick?

As I mentioned above, the bar for getting listed on API directories can be as simple as being added to a text file in Github - so you might as well list on all of the ones you can. Given a limited amount of time you might have while juggling everything else involved with developing an API, you might be wondering what's the best directory to list my API on? Here's a list of every API directory I could find across the entire internet, along with a little blurb on each. Please note that these opinions are solely my own.

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APIs.guru

• APIs Guru is one of the most popular directories, simply acting as a giant, alphabetically sorted list of APIs (2500+ apis)
• They require a machine-readable API definition, good thing you already have an OpenAPI file. They pre-process the doc to clean it up, fix bugs, and add necessary metadata
• How to Get Listed: Here's a direct link to get your API listed
• My Opinion: This directory needs a lot of love. Many of the APIs don't exist or have broken links. It's also crowded with hundreds of Amazon/Microsoft APIs - I don't think devs have a problem finding those
• Score: C, for Crashes my browser occasionally

Public-APIs Github Repo

• This Github repo is a barebones list of APIs, categorized by use-case, with one line descriptions. Simple and straight to the point. I believe there used to be a website, but its down now.
• How to Get Listed: View the contributing guide to get your API added
• My Opinion: Again, I'm unsure if this is being actively maintained, with the last contribution being in Sept 2023. There's also some drama with the ownership of this repo, which might be what's killing this project. Forks have been created, including a new website
• Score: D, for Drama alert

PublicAPIs.dev

• This website is the spiritual successor to the Public-APIs Github repo. Like its predecessor, it's open source - but also comes with a fancy website with categories and lets you filter and sort results. What's really nice is that you can report APIs, so junk APIs don't just accumulate
• How to Get Listed: Follow the contributing guide to add your API
• My Opinion: This is exactly what an API directory should be: open, well laid out, and easily searchable. I only have 2 gripes; The first is the lack of social proof that some other platforms have (ex. upvotes, companies using this, etc.). The second is the introduction of "Featured APIs" (essentially paid ads). If ads are what it takes to keep this project going strong, I can live with that
• Score: A, for Amazing example of a good API directory

APIList.fun

• This simple and intuitive website categorizes APIs (and allows for multiple categories per API). Some social aspects are introduced; like upvotes, comments, list of companies using the API
• How to Get Listed: You can use this form to submit your API
• My Opinion: Very few APIs are listed on this site, so I wonder if it gets significant traffic. This project is also sponsored by APILayer - which seems to be associated with the drama in public-apis (I have nothing against them, but its worth noting). Other than poor moderation on comments/company list - I don't see anything bad about listing here
• Score: C, for Could use more Content

API3 Alliance

• This is a list of API providers on Web3. Not much else to say
• How to Get Listed: You can submit your API using this form
• My Opinion: Is Web3 still a thing? Regardless, this directory provides very little context on your API other than a category. It also hides results under a "Load More" section - as if loading 15 URLs is bandwidth-intensive.
• Score: B, for Better than nothing in this space

Postman API Network

• Rather than being purely an API directory, this is a directory of Postman Public workspaces that are curated by Postman themselves
• How to Get Listed: Simply create a public workspace and I assume it will get indexed. This might be a bit laborious to setup if you don't already use Postman
• My Opinion: Postman does a good job with curation here, which can help good APIs stand out. I don't see the value in workspaces, however - users will still need to sign up on your site to obtain a key. Many docs platforms include test consoles now, so perhaps Postman is less necessary.
• Score: B, for Better than most on this list

AnyAPI

• AnyAPI is a simple categorizer of APIs, also providing a test console and docs
• How to Get Listed: It's unclear how to get your API listed, seems to be sourced from other directories
• My Opinion: This site doesn't seem to be updated anymore, and testing is broken for me. Also associated strongly with APILayer it seems (I have nothing against them but it is worth noting)
• Score: D, for Don't recommend

APIs List

• APIs List is a more recent entrant (launched on PH 2 years ago) and is a curated list of APIs.
• How to Get Listed: I'm unsure how to submit an API, but here's their contact page
• My Opinion: The categorization is quite detailed compared to other directories. Not much else to say.
• Score: B, for Best categorization system

APIS.IO

• APIs.IO is an index of APIs in the most raw sense. Some limited scoring of the APIs is performed, but otherwise, all results come from an APIs.json file you create.
• How to Get Listed: Here's a direct link to get your API listed
• My Opinion: I have no clue how popular this is. I assume creating an APIs.json file isn't too hard, so probably worth trying
• Score: C, for Can be interesting to play with, but needs more volume of results and better ranking to be taken seriously

API Expert + API Context API Directory

• All directories aim to make picking an API easier, but API Expert takes a different approach, focusing on depth instead of breadth. It surfaces extremely detailed performance and reliability metrics, as well as a built-in scoring system, on a carefully curated set of APIs. For a more directory-level view of the same APIs, you can use API Context's API directory
• How to Get Listed: You will need to contact APIContext directly
• My Opinion: I'm unaware of any other site that benchmarks APIs like this - definitely useful information when making a decision. I wish it had more APIs however (ex. Adyen for Fintech)
• Score: B, for Breadth should be the next focus imo - make it easy to compare the most popular APIs in each category

API Tracker

• This platform has A LOT of potential. Not only does it have breadth (5000+ APIs), but it also has depth (OpenAPI specs, postman collections, alternatives). What's the catch? The website has some performance issues making loading pages take forever
• How to Get Listed: I didn't see a way to add your own API (site seems mostly autogenerated) but you can contact them and see what they say
• My Opinion: In term of the raw amount of data available, this directory is reigns supreme. Ignoring some minor performance issues, there is a lack of polish across the site (ex. certain pages are just empty, others don't have data you are expecting) but that's also to be expected with how ambitious this project is
• Score: A, for Access to information is unparalleled

Final Thoughts

I had no clue that there were so many API directories, and how many have risen and fallen. In general, I have a positive outlook on the space based on more recent projects. Have you used any of these directories before? I'm curious to learn how much traffic you got from them.

Next Steps

You might be wondering why popular API listing sites like RapidAPI were not listed here. That's because I consider them API Marketplaces, which I discuss in this in-depth guide to API marketplaces. You can also read our Ultimate Guide to API Promotion and Marketing for a more holistic understanding of the problem.