Application programming interfaces, or APIs, are the backbone of web development. They give developers access to a wealth of functionality and data, making it easy to build custom software or integrate with preexisting services. Today's top APIs cover everything from e-commerce and payments management to customer relationship management (CRM) and lead-tracking software. Whether you're looking to integrate your app with a CRM system or add some e-commerce functionality to an online store, these powerful APIs can help you get the job done in no time.

This article will look at some of the most popular and useful APIs for web developers and programmers. After all, why reinvent the wheel? APIs will enable you to quickly and easily add new features to your apps and websites with minimal effort.

Let's dive right in!

We'll cover:

What is a web API?
Anatomy of an API
The 6 types of APIs
16 great APIs for web development
More APIs and resources
- API documentation
Wrapping up and next steps

What is a web API?

An API is a set of instructions that software developers can use to access features and functions of other software. In other words, an API allows two pieces of software to communicate with each other. When you use an API, you are essentially using someone else's code to power your application. For example, when you use the Google Maps API to add mapping functionality to your website, you use code written by the Google Maps team.

The most common type of API is the web API, which can be accessed over the internet using HTTP. It's typically used with JavaScript to add features during web development. Other APIs include local APIs, mobile APIs, and machine-to-machine (M2M) APIs, but we'll be focusing on web APIs for now.

Anatomy of an API

An API request is made up of four parts:

Method: The HTTP method used to make the request, such as GET, POST, PUT, or DELETE
URL: The address, or, endpoint, of the API web server from which you're requesting data
Parameters: The data that is sent to the server side of the API in the request
Headers: Used to authenticate the request and specify the format of the data being requested

An API response also consists of four parts:

Response code: The HTTP status code returned by the API to indicate whether the request was successful or not. The most common response codes are 200 (OK), 404 (Not Found), and 500 (Internal Server Error)
Data: The data returned by the API in JSON or XML format
Headers: Used to specify the format of the data being returned
Links: Used to paginate data or provide information about related sources

API endpoints are the URLs used to send requests to an API. For example, the Twitter API has an endpoint for retrieving tweets (https://api.twitter.com/1.1/statuses/user_timeline.json) and an endpoint for searching tweets (https://api.twitter.com/1.1/search/tweets.json).

API resources are the data you request from an API. For example, tweets are considered a resource of the Twitter API. In the same way that an endpoint is the URL of an API, resources are the data you request from API URLs.

API keys are used to authenticate your requests to an API. They are generally passed in the headers of your requests. For example, the Twitter API requires that you use an API key when making requests to its API.

The 6 types of APIs

Each API has certain parameters and rules that govern how and when it can be used^[1]. Some APIs allow for unrestricted access and require no authentication or authorization from the client side. Other APIs have stricter usage guidelines and may require users to submit certain information before accessing the provider's features and functions.

Here are some APIs with different usage guidelines:

Open APIs allow free access or usage by a third party.
Partner APIs allow commercial entities to work together in an open ecosystem with developers and companies. These APIs can be free or paid. The Airbnb API and eBay APIs are two examples of partner APIs.
Public APIs are similar to open APIs and tend to have some form of payment structure. Public APIs tend to be some of the most reliable and well-developed APIs available.
Private APIs are only available to those with permission or a password from the company that controls it. These are the most common type of API because they're not meant for public consumption, which makes developing them a bit faster.
Composite APIs are made up of two or more APIs that combine an ordered sequence of several API requests into one API call that receives one response. Batch APIs are similar, but the sequence of API requests being made does not affect the response.
Unified APIs are similar to composite APIs in that they combine various API and back-end resources into one. They're aggregators, frequently combining common features or APIs from a certain industry, such as banking or CRM solutions. Stripe, a financial SaaS platform, is one example of a unified API.

16 great APIs for web development

We'll be going over 16 of the most commonly used APIs and what they can contribute to your next web development project.

#1-3: Amazon APIs: Product Advertising, DynamoDB, and Amazon Simple Storage Service (S3)

Amazon provides a number of free APIs that can be used in web development projects. Although these APIs are most often used for eCommerce applications, they can also be used for other purposes.

Note: You can use the Amazon API Gateway pricing calculator to get a custom estimate for your web application. The Free Tier includes one million API calls received for REST APIs or HTTP APIs, and one million messages and 750,000 connection minutes for WebSocket APIs per month for up to 12 months^[2]

Amazon Product Advertising API

The Amazon Product Advertising API^[3] is one of two free Amazon APIs, the other being Amazon Marketplace Web Service (MWS), which will be deprecated after December 31, 2023.

The Product Advertising API allows developers to access Amazon's massive product catalog and retrieve information on products such as prices, availability, and customer reviews. It offers a wide range of features that can be integrated into a website or mobile device applications and includes support for banners, product listings, videos, coupons, and more.

Some of its resources include:

Images: Returns the URLs for all available images of an item in three sizes: Small, Medium, and Large
VariationSummary: Provides the lowest price, highest price, and variation dimensions for all variations in an API response.
Offers: Contains various resources related to offer listings and item summaries

The Product Advertising API supports the following operations:

GetBrowseNodes: Look up information for a Browse Node
GetItems: Look up item information
GetVariations: Look up information for variations
SearchItems: Searches for items on Amazon using keywords

If you're looking to display advertising content on your web applications or build Amazon-integrated apps that enable customers to shop directly via the app, then the Amazon Product Advertising API is a solid option to consider.

Again, the Product Advertising API is free^[4]. All you need to do is sign up to become a Product Advertising API developer.

Note: Most accounts will be limited to 50 requests per second, but higher limits are available for some accounts.

Amazon DynamoDB API

The Amazon DynamoDB API is designed to be used with the AWS SDK and allows developers to access and manipulate data stored in Amazon DynamoDB tables. DynamoDB is a fast and scalable NoSQL database service that is commonly used in distributed database management systems.

The DynamoDB API is most useful for applications where you need fine-grained control over your data or for applications that need to perform DynamoDB operations in a high-performance environment with high availability.

Here are a few DynamoDB API operations:

PutItem: Creates a new item or replaces an existing one with a new item
GetItem: Retrieves an item from a DynamoDB table
UpdateItem: Modifies an existing item in a DynamoDB table

Note: Some of DynamoDB API's endpoints allow for DynamoDB Streams, which provide a time-ordered sequence of item-level changes on a DynamoDB table. This can be useful for building event-driven applications that need to respond in real time to changes in data.

If you're looking to add support for DynamoDB to your applications, then check out the DynamoDB API documentation.

Amazon Simple Storage Service (S3) API

The Amazon S3 API is an object storage API that allows developers to store and retrieve data used by web applications, such as images, videos, and user-generated content, from Amazon's S3 storage service.

The Simple Storage Service^[5] uses buckets to store data, each bucket acting as a container for objects. In addition, the S3 API has high availability thanks to its use of cloud technology and is sometimes used to store data for backups or disaster recovery.

It's also easy to use! Web developers can quickly create web applications that upload and download files to and from Amazon S3 web servers using this API.

#4-6: Google APIs: Google Maps, Google Calendar, YouTube Data API

Google APIs are some of the most popular and well-documented web APIs available. While most of the Google APIs are free to use, some require an API key. Here are a few essential Google APIs you may find useful in your next web development project.

Note: Google APIs charge for usage, and you will need to enable billing before you can start using these APIs.

Google Maps Platform APIs

The Google Maps Platform provides some of the most popular and widely used Google APIs, and there are a great number of ways you can use these APIs to add functionality to your website or application.

At the time of writing, there are eight Web Service APIs on the Google Maps Platform:

Direction API: Directions between multiple locations
Distance Matrix API: Travel time and distance for multiple destinations
Elevation API: Elevation data for any point in the world
Geocoding API: Converts between addresses and geographic coordinates
Geolocation API: Location data from cell towers and WiFi nodes
Places API: Up-to-date information about millions of locations
Roads API: Snap-to-road functionality to accurately trace GPS breadcrumbs
Time Zone API: Time zone data for anywhere in the world

The Google Maps Platform offers flexible pricing and a $200 monthly credit if you want to try it out before buying.

However, you'll need a Google developer account to get started. Furthermore, if you plan on using the Google Maps API for commercial purposes, you'll need to purchase a Google Maps API license.

Google Calendar API

The Google Calendar API is a great way to add calendar functionality to your web applications. The API allows you to create, retrieve, update, and delete events from a user's Google Calendar. You can also use the API to manage calendar resources, such as calendars, events, and guests.

Some of the Google Calendar API resources include:

Calendars: A collection of all existing calendars
Events: A collection of different types of event objects associated with a specific date or time range
Freebusy: Returns free/busy information for a set of calendars

YouTube Data API

The YouTube Data API allows developers to access and manipulate data from YouTube. You could use this API to display a list of videos, allow authorized users to upload videos to YouTube straight from your website or application, and much more.

The YouTube Data API uses resources, which they define as "an individual data entity with a unique identifier^[6]."

Here are some of the resources you can interact with using the API:

channel: Contains information about a single YouTube channel
subscription: Contains information pertaining to a YouTube user's subscription, such as when a user uploads, rates, or comments on a video
videoCategory: Identifies a category that has been or could be associated with uploaded videos

Developers can interact with these resources and more using the following operations:

list: Retrieves (GET) a list of zero or more resources
insert: Creates (POST) a new resource
update: Modifies (PUT) an existing resource to reflect data in your request
delete: Removes (DELETE) a specific resource

Note: If you decide to give these APIs a try, be sure to follow this tutorial on how to use OAuth 2.0 to access Google APIs.

#7-8: Social Media APIs: Facebook and Twitter

Social media APIs are among the most commonly used web APIs. They allow developers to access data from social media platforms like Facebook and Twitter.

Each social media platform has its own API that developers can use to interact with the platform's data. You must create a developer account with each social media platform to use these APIs. Once you've done that, you can generate an API key and use it to access the platform's data.

Let's get started by looking at the Facebook Graph API.

Facebook Graph API

The Graph API is the primary way to get data in and out of Facebook. The Graph API is named after the concept of graphs as data structures, which are collections of nodes (vertices) and edges (lines). In the case of the Facebook Graph API, you can think of the nodes as Facebook pages, posts, and users, while the edges represent the connections between them.

In order to use the Graph API, you'll need to create a Meta developer account and generate an access token. Next, you can use that access token to make requests to the Graph API endpoints. Then, you'll receive a response in JSON format (by default), which you can then parse and use as you see fit.

A few Graph API endpoints include:

Page: /{page-id} gets information about a specific Facebook page
User: /{post-id} Gets information about a specific Facebook post
Message: /{user-id} Gets information about a specific Facebook user

The Facebook Graph API is free to use in all cases, commercial or otherwise. However, rate limits apply. Rate limits are defined as the maximum rate for which a specific account can request resources from an API in a given time period. The rate limit is applied to all GET requests to the API, regardless of the resource requested. There are two different types of rate limits: daily and per minute. A daily rate limit means that a user can only make a certain number of requests per day. This limit is applied at the Account level and cannot be adjusted by users.

Twitter API

The Twitter API is a RESTful API that allows web developers to access data from tweets, timelines, and Twitter users. You can use the Twitter API to collect data for analyzing trends, build applications that interact with Twitter users (such as Tweetbots), and more! It's a highly configurable API with many different endpoints for retrieving data in various ways.

You can use the following operations with the Twitter API:

GET retrieves a specific resource
POST creates a new resource
PUT updates an existing resource
DELETE removes a specific resource

Here are some examples of endpoints listed under the Tweets resource in the documentation for Twitter API v2:

Likes: POST /2/tweets/:id/likes causes the user ID identified in the path parameter to like the target tweet
Manage Tweets: POST /2/tweets creates a tweet on behalf of an authenticated user
Retweets: POST /2/users/:id/retweets causes the user ID identified in the path parameter to retweet the target tweet

You can view a complete list of Twitter API endpoints in their API reference index.

Developers can sign up to use the Twitter API based on a tiered access model. Currently, there are three tiers available:

Essential: Provides access to Twitter API v2 and standard v1.1
Elevated: Provides access to premium v1.1, enterprise, and everything in the Essential tier
Academic Research: Access to all of the above with fewer limits

They also have a suite of Enterprise APIs available for those interested in more powerful solutions.

You can view the complete table of Twitter API access levels in the documentation of their Developer Platform.

#9: Stripe API

Payment-processing or payment request APIs allow developers to add payment-processing functionality to their applications easily. This can be useful for eCommerce applications, subscription services, or even just for accepting donations. One of the advantages of using a payment request API is that you don't have to worry about setting up your own payment processing infrastructure, which can be costly and time-consuming. Furthermore, using a well-established payment processing service tends to be more secure, as they will have robust security measures in place.

Stripe is a payment processing platform that offers a suite of APIs. One of the most reliable payment processing platforms, Stripe has been around since 2010 and processes billions of dollars annually for businesses worldwide. It's a great option for those looking to add a payment gateway to their e-Commerce websites or mobile applications.

What is a payment gateway?: A service that allows you to accept credit cards and other types of payment in your web application. The gateway is a middleman between your website and the customer's bank to facilitate the transaction.

Some of the features of the Stripe API include:

Easy activation: You can start using the Stripe API immediately after signing up, and their onboarding process is very user-friendly
Developer-friendly: Stripe provides production-build-ready libraries and SDKs, and world-class support for integration with legacy applications
Global reach: Stripe is available for business in 47 countries and accepts payments from anywhere in the world.
Optimized revenue: Stripe leverages machine learning technology to detect fraud and increase authorization rates for every transaction.
Payments for business: Stripe provides a robust and comprehensive suite of solutions for businesses and e-Commerce

Another thing to remember is that Stripe objects are the core building blocks of the Stripe API. These objects represent resources like customers, charges, and refunds. Each object has its own set of properties and methods that you can use to retrieve data or take action on that object^[7].

Here are a few examples of how these resources can be used:

Balance: GET /v1/balance retrieves the current account balance based on the authentication that was used to make the request
Events: GET /v1/events lists all of the events going back up to 30 days
Customers: POST /v1/customers updates the specified customer by setting the values of the parameters passed

Other popular payment processing APIs include the Square API and PayPal API.

#10: AccuWeather APIs

Weather APIs are useful for creating a wide range of applications, from personal weather tracking apps to agricultural applications for monitoring conditions for crops.

The AccuWeather APIs provide access to data and forecasts for over 100 million locations worldwide.

Some AccuWeather APIs include:

Locations API: Gets a location key for your desired location, and uses the key to retrieve weather data from the Forecast or Current Conditions API
Forecast API: Gets forecast information for a specific location
Current Conditions API: Gets the current weather conditions for a specific location

You can check out a full list of AccuWeather APIs by checking out their API Reference page.

The AccuWeather APIs use a 4-tier pricing model:

Free: $0/month
Standard: $25/month
Prime: $250/month
Elite: $500/month

Their Free plan provides access to locations, current conditions, and historical weather data for the past 24 hours. In addition, you will have access to an hourly forecast spanning 12 hours and a daily forecast spanning five days. You can accomplish a lot using these endpoints alone, and it's completely free! Consider making it a weekend project to implement the AccuWeather API in a web application.

If you want alarms, translations, imagery, and more, you'll need to sign up for one of their paid tiers, starting at $25/month.

Note: The AccuWeather API is not free for commercial use. If you plan to use the API for commercial purposes, you will need to purchase a commercial license.

Popular alternatives to the AccuWeather APIs are the Weather Channel API, Yahoo Weather API, and the OpenWeatherMap API.

#11: Crunchbase API

The Crunchbase API is a read-only RESTful service that leverages Crunchbase Data to incorporate industry trends, investment insights, and company data into web applications. Crunchbase was originally built to track startups, but they now track both public and private companies worldwide.

Crunchbase insights and analytics can be used to discover companies that match your ideal target prospects, identify individuals to reach out to with verified contact data, and connect with decision-makers right within Crunchbase^[8].

Access to the full API requires an Enterprise or Applications license.

Crunchbase Basic provides access to a limited set of Organization data fields using the 3 API endpoints below:

Organization Search: POST /searches/organizations performs complex filtering based on the query defined in the request body
Organization Entity Lookup: GET /entities/organizations/{entity_id} looks an organization up
Autocomplete: GET /autocompletes suggests matching Identifier entities based on the query and entity_def_ids provided.

Crunchbase utilizes a four-tier pricing structure:
Basic: $0/month
Starter: $29/user/month (billed annually)
Pro: $49/user/month (billed annually)
Enterprise: Custom pricing

While there are no limitations on how you use the dataset to power your own applications, you are required to attribute Crunchbase when using their dataset.

Popular alternatives to the Crunchbase API are PitchBook Data and Clearbit.

#12: REST Countries API

The REST Countries API provides free access to data about all countries in the world. It includes geographical information such as country names, capitals, official languages, etc. Developers can use this API to quickly create applications that display information about countries or filter results by a specific keyword or category.

A few of their endpoints are:

Name: https://restcountries.com/v3.1/name/{name} searches by country name (native or partial names supported)
Language: https://restcountries.com/v3.1/lang/{lang} searches by language name
Currency: https://restcountries.com/v3.1/currency/{currency} searches by currency name

Note: The REST Countries API does not have a tiered pricing structure, but they do accept donations! If you use the API and find it useful, consider donating to help with the cost of upkeep.

#13: Auth0 Authentication API

The Authentication API outsources the authentication process to Auth0. When your user authenticates, Auth0 generates an ID Token and Access Token that is passed back to your web application. The Access Token can then be used to call your API^[9].

Some of their endpoints include:

Login: GET /authorize authenticates a user with a social provider. Returns a 302 redirect to the social provider specified in connection
Logout: GET /v2/logout logs a user out of a web application
Change Password: POST /dbconnections/change_password, given a user's email address and a connection, Auth0 will send a change password email. This endpoint only works for database connections

Auth0 has flexible pricing options that are highly customizable to fit your needs. So if you're looking to use Auth0 on an enterprise scale or have a complex use case, be sure to contact them.

Here are a few of the pricing plans available with Auth0:

Free: $0/month
B2C Essentials: $23/month
B2C Professional: $240/month
B2B Essentials: $130/month
B2B Professional: $800/month

Popular alternatives to the Auth0 Authentication API include the Keycloak API and OneLogin API.

#14: Spoonacular API

Spoonacular advertises their API as "the only food API you'll ever need."

You can use the Spoonacular API to:

Find recipes to use ingredients you already have
Find recipes based on nutritional requirements
Extract recipes from any webpage
Classify a recipe's type or cuisine
Generate an entire meal plan
Generate shopping lists
Perform a UPC lookup of American grocery products
Detect food in text (NER)
Find food trivia and jokes
Create a chatbot

Here are a few of the Spoonacular API endpoints:

Compute Ingredient Amount: GET https://api.spoonacular.com/food/ingredients/{id}/amount calculates how much of a certain food you would have to eat to get a certain amount of vitamins, fiber, protein, etc.
Analyze Recipe: POST https://api.spoonacular.com/recipes/analyze allows you to send raw recipe information (such as title, servings, and ingredients) and receive an analysis using Spoonacular's algorithm
Compute Shopping List: POST https://api.spoonacular.com/mealplanner/shopping-list/compute returns a shopping list if you send a list of ingredients

Spoonacular regularly updates its API with new endpoints for different use cases and has well-maintained documentation, making it a perfect API for beginner web developers to try implementing.

The API has five tiers to its pricing model:

Free: $0/month
Cook: $29/month
Culinarian: $79/month
Chef: $149/month
Enterprise: Starts at $300/month

#15: Spotify Web API

Spotify provides a RESTful web API that returns JSON metadata about music artists, albums, and tracks from the Spotify Data Catalogue. The Spotify Web API also provides limited access to user-authorized private data like playlists and music that users save in the Your Music library.

One of the great things about the Spotify Web API is that it's well-documented, meaning that it's easy to get started with and use their API. You can find the Spotify Web API in the documentation on Spotify for Developers.

Here are just a few of the many Spotify Web API endpoints:

Get Album: GET /albums/{id} gets the Spotify catalog information for a single album
Add Items to Playlist: POST /playlists/{playlist_id}/tracks adds one or more items to a user's playlist
Search for Item: GET /search gets Spotify catalog information about albums, artists, playlists, tracks, shows, episodes, or audiobooks that match a keyword string

The Spotify Web API is available to anyone, free of charge. However, if you're interested in using the Spotify Web API for commercial purposes, be sure to check out their Developer Policy, Complying with Spotify's Developer Policy, and Developer Terms. In addition, be sure to check out their policy for Commercial Use.

One popular alternative to the Spotify API is the SoundCloud API.

#16: GIPHY API

The GIPHY API can be used to integrate the world's largest GIF and video library into your web application with just minimal coding. Users can query their GIF search engine in over thirty languages.

Here are a few of the endpoints that GIPHY API provides:

Trending: Returns a list of relevant content seeing a high level of engagement amongst users
- GIF URL: api.giphy.com/v1/gifs/trending
- Sticker URL: api.giphy.com/v1/stickers/trending
Search: Grants access to the GIPHY library of GIFs and Stickers by querying their search algorithm
Translate: Converts words and phrases to a GIF or Sticker using GIPHY's algorithm

They even have a quickstart guide to help you get started.

The GIPHY API is free for anyone and, as a bonus, has thorough documentation. If you're interested in using it in a software application, you may want to check out the GIPHY SDK License Agreement beforehand.

Another popular alternative is the Tenor API.

More APIs and resources

As of 2022, there are thousands of APIs available to the public, and choosing one can be a daunting task if it's your first foray into using APIs in web development. However, it's absolutely worth your time to learn how APIs work and how you can implement them in your projects. Web APIs have become ubiquitous, and there aren't many software applications that do not offer some form of web API these days^[10].

If you're looking for a place to start, you'll find that the RapidAPI Hub is an excellent resource for browsing all kinds of APIs. You can even take a gander at curated lists of popular or recommended APIs based on the functionality offered, performance, support, and more.

Another great resource is this GitHub repository for APIs.

API documentation

One of the most important things to consider when choosing an API is the quality of its documentation. A well-documented API will save you tons of time and headaches in the long run and make it easier for you to start using the API in your project. This is especially true if the API documentation comes with a guide to getting started.

Here are a few things that good API documentation should always include:

Resources: Description of the information being returned by an API
Endpoints and methods: Up-to-date documentation of the available endpoints that an API offers, what resources they access, and the interactions (such as GET) each resource supports
Parameters: Descriptions of the different options you can pass with the endpoints to influence the response (e.g., header parameters, path parameters, etc.)
Example requests and responses: One or more example requests for each endpoint, along with corresponding responses

In addition, good API documentation should be easy to navigate and regularly updated to reflect any changes that are made to the API. If the API has a pricing model or rate limitations, it's expected that the documentation will also include this information.

Other good-to-haves:

Error codes: A list of all possible error codes that can be returned by the API, along with a description of each error code
Authentication: A description of how to authenticate with the API, if necessary
SDKs: A list of all available SDKs for the API (if any), along with a description of each SDK's functionality

It's also a good sign if the API documentation provides a way to contact the API provider (e.g., email, website, Twitter) if you have any questions or need support.

Wrapping up and next steps

By now, you should have a solid introduction to several APIs that are used widely by other web developers. Where you want to go from here depends on your specific learning goals. If you want to learn more about the basics of APIs, then consider brushing up on the differences between Simple Object Access Protocol (SOAP) APIs, Remote Procedure Call (RPC) APIs, Websocket APIs, and Representational State Transfer (REST) APIs. Or, if you want to prepare for an upcoming interview, try quizzing yourself on API interview questions, and consider checking out some of our courses.

To get started learning these concepts and more, check out Educative's Become an API Integrator learning path.

Happy learning!

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16 great web APIs to use in web development