APIs quietly run most of the internet you use every day, and once you start looking at the numbers behind them, the scale is genuinely hard to picture. This post collects some of the most striking statistics, case studies, and stories about APIs, along with a few public APIs you can play with yourself. Think of it as a tour of why APIs matter, told through facts rather than theory.
Some Amazing API Statistics
The daily call volumes at large platforms are staggering. Google receives around 5 billion API calls daily. Twitter receives roughly 13 billion. Facebook receives about 5 billion, and Netflix around 10 billion. Klout, in its time, handled about 1 billion calls a day.
The dependence goes deeper than raw volume. Around 60 percent of eBay transactions happen through their API, and roughly 50 percent of Salesforce transactions come from APIs rather than the web interface. Netflix uses its API to stream across more than 200 device types. Finance is the top sector where APIs operate at massive scale.
Postman’s growth tells the same story from a developer’s angle. In 2016, Postman had fewer than half a million collections, the folders developers use to group related API requests. By January 2021 that had shot past 46 million collections, and Postman has tracked billions of API requests in a single year. If you are weighing tools, it is worth understanding where Postman fits and where it does not before committing a workflow to it.
API Adoption and the Four Main Types
API use has grown roughly 13 times since 2007. API Friends, a community for people who work with APIs, groups them into four main types.
Open APIs, also called public APIs, are available for anyone to use. Partner APIs give limited access to a company’s services through approved integrations with other platforms. Internal APIs, also known as private APIs, are used only within a company. Composite APIs bundle multiple data streams or actions into a single call, so you do not need a separate API request for each component.
Life Without APIs
It is easier to appreciate APIs by imagining their absence. With an API, a like button on your website can register a like on a Facebook post automatically. Without one, you would have to instruct every user to open Facebook, navigate to the page, and like the post manually. The same is true of sharing: a share button lets LinkedIn post to your profile in one click, whereas without an API you would copy the content and post it by hand. APIs remove that friction everywhere they are used.
A Few Memorable API Moments
Some real-world events show what APIs handle under pressure. During an India versus New Zealand cricket match, Hotstar set a record with its API serving live content to 25 million concurrent viewers. They had prepared for that surge with load testing on a priority basis, using 108,000 CPUs and 216 TB of RAM. During Flipkart’s Big Billion Day sale, over 66.6 crore visits were recorded, with Flipkart’s APIs handling around 100 orders per second.
Public APIs You Can Play With
If reading about APIs makes you want to build something, the fastest way to learn is to call a few. There are large directories of free, public APIs covering everything from weather to trivia, including collections of random facts APIs you can wire into a small project in an afternoon.
Frequently Asked Questions
What is an API in simple terms?
An API, or application programming interface, is a set of rules that lets one piece of software request data or actions from another. It is the contract that lets a website, app, or service talk to another over the network.
What are the four main types of APIs?
They are open or public APIs available to anyone, partner APIs shared with approved external parties, internal or private APIs used within a company, and composite APIs that combine several calls into one.
Why are APIs so important to modern applications?
APIs let applications reuse each other’s data and functionality instead of rebuilding everything from scratch. Features like social sharing, payments, maps, and live data feeds all depend on APIs, which is why platforms like Google and Netflix field billions of calls a day.
Where can I find public APIs to practice with?
Public API directories such as RapidAPI list thousands of free APIs by category. Starting with something simple, like a weather or random-facts API, is a good way to learn how requests and responses work.
