Top 7 Popular Free APIs of 2021

APIs have been on the rise for many years. They’re an essential component of the data-driven ecosystem, as well as CI/CD, which gets increasingly popular with each passing year.

Consider these predictions on digital transformation from ZDNet, about the trends that will shape the digital landscape in 2021.

Digital Transformation Trends For 2021:

  1. The digital-ready culture
  2. Democratization of innovation
  3. Composable enterprise
  4. Automation
  5. API Security
  6. Microservices
  7. The data divide
  8. Data analytics

APIs play an important role in nearly every one of those trends. APIs were already well on their way towards being ubiquitous well before 2020. The complications brought on by Coronavirus have put those innovations into warp drive, though. Constant connectivity, remote access and collaboration, and the need for efficiency have made APIs essential for companies looking to weather the storm.

Of course, any time there’s a massive influx of interest and hype, there’s a frenzy of people looking to capitalize on the attention. A head-swirling array of new APIs are being released every day. This raises the question: which ones are actually useful and which ones are glorified gimmicks?

The API marketplace RapidAPI recently released their list of the Top 50 APIs For 2021 based on their own research and analytics. Below, we’ll review the top seven as a barometer of the most popular and useful APIs at the moment.

The Top 7 Most Popular APIs For 2021

Skyscanner API

Google recently deprecated their own Google Flights API, leaving a vacuum for developers looking to create travel apps. Surprisingly, considering the world’s current travel state, the #1 most popular API on RapidAPI is the Skyscanner API, a search engine for travel and flight data, hotels, car rentals, and more.

The Skyscanner API offers an impressively thorough list of endpoints that should more than meet any needs you may have when developing a travel app. These include:

  • Browse Dates
  • Browse Quotes
  • Browse Routes
  • Create session
  • Currencies
  • List Places
  • List markets
  • Poll session

Just as impressively, Skyscanner’s entirely free to use.

Skyscanner’s not just for travel agents or frugal travelers, either. It has potential uses for travel providers themselves. They recently unveiled a new feature showcasing unserved routes. This could give the airlines insights into how they might continue to grow once travel recommences.

Whether Skyscanner’s popularity is merely aspirational thinking from a stir-crazy world or forward-thinking developers looking to take advantage of the inevitable travel boom that’s going to take place once lockdown ends, it’s hard to say. One thing is for sure — nearly 100 million app downloads don’t lie. Developers are likely finding Skyscanner’s API useful as well!

Open Weather API

Surprisingly, the second most popular API on RapidAPI is a weather API. It’s not just any weather API, though — OpenWeather API is the official API of OpenWeatherMap, the company that’s been providing weather stations with their data since 1979.

OpenWeather API also features an impressive array of useful endpoints. These include:

  • Current Weather Data
  • Daily Forecast Weather Data
  • Forecast Weather Data
  • Search Weather Data

OpenWeather API’s data is gathered from over 40,000 weather stations located all over the globe. Developers have been discovering new and innovative ways to integrate this weather data, as well.

They’ve integrated OpenWeather into Google AdWords, for example. The rationale they offer is that outdoor entertainment companies, for instance, are likely to be much more prevalent when the weather’s nice than when it’s cold and rainy. Amusement park owners might want to reduce their ad spend on days when it’s rainy and increase it when the sun’s out.


“Football” is soccer to the rest of the world that is not the United States. API-Football is the API that brings you more soccer-related stats than you can shake a pair of cleats at.

API-Football is suitable for more than checking the scores of your favorite teams, also. The API also provides pre-game odds, upcoming events, team line-ups, current rankings, and other stats. It’s useful for everything from creating a simple tracker, for the uber-sports enthusiast, to powering sports betting sites, to creating your own fantasy football, er soccer, leagues. It can even be used to make predictions, suggesting API-Football could even be used for machine learning applications.

API-Football is free for up to 50 calls a day, with several other pricing levels beyond.

Cocktail DB API

Tired of drinking the same old thing after ten months of lockdown? Looking to create that Road House app you’ve always dreamed of? Simply wondering what on Earth you can do with vermouth? The surprisingly deep Cocktail DB API has you covered!

The API for the Cocktail database is not just another bartender’s bible, either. Cocktail recipes also feature user’s photos and tags, so you can search drinks for flavor, origin, even the best drinks for specific meals.

The Cocktail DB API even features recipes for non-alcoholic drinks, in case you want to learn to mix a Shirley Temple. The ability to make your own lists seals the deal, so you can make lists of all the whiskey drinks you want to try. Here’s your chance to make drinking at home more fun and interesting until the pubs return to normalcy later in the year.

REST Countries

REST Countries v1 is a simple premise with all manner of potentially useful applications. Simply put, it does what its name suggests — providing useful data about a country in REST format.

REST Countries v1 offers a number of potentially useful endpoints, from names to country codes to currency. While it’s a fairly simple service, REST Countries v1 is completely free, having recently been acquired by apilayer. It’s already used by over 1200 clients, ranging from Spotify to vacation sites like onefinestay and Much Better Adventures. Even the indie rockers the Gorillaz have found a way to integrate REST Countries v1. If it’s good enough for Noodle and 2-D, it must be worth a look!

Yahoo Finance

Yahoo may no longer be on the cutting edge of search engine algorithms or breaking news, but this API is a go-to for up-to-the-second financial data. And while cocktail data and soccer scores may be good for some fun programming assignments, an API that deals with cold, hard cash might be more of a cause for celebration — especially when that API offers a free tier.

The Yahoo Finance API offers even more than strictly financial data and records for those who follow economics closely. There are numerous endpoints for sorting your watchlist and portfolio, for one thing. Another endpoint offers news stories around various stocks.

At the least, one could use the Yahoo Finance API to power a financial news app or browser, saving you from having to browse 100 different investment news sources. At best, you could use it as the backend for your own investment app or machine learning resource. Getting real-time financial data is always tricky, so finding one that allows up to 500 calls a month for free is worthy of celebration!

URL Shortener API

Some of the APIs on our list have been exciting. Others have been entertaining. APIs are often an integral utility for the backend, though — essentially operating as part of the plumbing or HVAC. The need to incorporate many pre-built services to take care of some of the mundane tasks in our development projects is one reason APIs are so useful and popular.

The URL Shortener API is a no-muss, no-fuss barebones utility API. Simply send a URL to the API with a POST request and get a shortened URL returned. The URL Shortener API is completely free and able to make up to 3 requests a second.

The State Of Free APIs In 2021

This is just a short synopsis of some of the countless useful and interesting APIs listed in the RapidAPI directory. Considering how data-driven our world has become, on top of the challenges raised from Coronavirus/COVID–19, the floodgates will likely remain open, pouring out a stream of useful cloud-based services for developers to integrate into their projects.

In the meanwhile, these seven should give you some idea of what’s out there and provide fodder for your own API investigations, as they’re all free and come well-recommended.