Unparalleled suite of productivity-boosting Web APIs & cloud-based micro-service applications for developers and companies of any size.


API Keys: Why and When to Use API Keys

a person in a white crew neck t-shirt using a laptop

API usage has increased rapidly in recent times. Almost every project uses APIs for data exchange. One of the most common examples in today’s software architectures is the communication of Frontend applications with Backend applications via an API. Additionally, in microservice applications, it is possible for services to communicate with each other in sync via an API. When we want to deal with the security factor of these APIs, the concept of API keys comes up. So what are API keys?

Ensuring API security is actually a very important step that should be considered before API development. There is more than one way to secure an API. One of these ways is the use of API keys. In this article, we will first find an answer to the question, ‘What are API keys.’ Then we will cover many more informative topics about API keys.

What are API Keys?

An API key is a special value that is required to use the API that an application or project offers to its users. An API key can be thought of as a “door key” as an analogy. Users use this key to access the API, and the API key is used to authenticate clients and enforce authorization checks.

For example, we develop an online forum application. In this application, we may ask users to access their own comments from different devices. For this, we create one of the user-specific project API keys and give it to the user. As a result, the user accesses his own data by making an HTTP request to the API we provide to the user with this API key.

Why API Keys are Essential for Secure Communication?

API keys are required to provide secure communication between applications. Because API keys provide access control to the API of an application or service. Users use the API key to authenticate and authorize their access. Thus, app owners ensure that only authorized users can access the API.

Without the API key, anyone can send requests to the API and access the data. This leads to security vulnerabilities and the possibility of malicious use. For example, anyone with access to an e-commerce platform’s API could gain unauthorized access to users’ personal data or order information. API keys mitigate such risks by allowing clients to access the API securely.

When to Use API Keys?

Firstly, API keys are used for authentication and authorization. Users authenticate using API keys to access the API and can only perform authorized transactions. Additionally, API keys also play an important role in third-party integrations. This simplifies the integration processes and provides secure access to the API.

Furthermore, API keys enable the enforcement of service quotas and limitations. For example, the API service provider may limit API usage based on the number of API calls or bandwidth in a given period of time.

Finally, developers can use API keys to monitor, analyze, and report API usage. By associating each API call with a key, they can collect usage data and determine usage trends.

Best Practices for Managing and Creating API Keys

There are some best practices for managing and generating API keys. Some of these are as follows:

  • Strong Key Generation: It is important to generate strong and complex API keys. Keys must be long enough, with random characters, and unpredictable. Strong random number generators or encryption algorithms can be used for this.
  • API Key Rotation: It is important that API keys are rotated regularly. Changing keys after a certain period of time or after a certain event is important for security. Thus, businesses that perform key rotations easily block potential attacks.
  • Monitoring and Logging: Monitoring and recording the use of API keys is important for security audits. Recording key information and usage statistics for each API call helps to detect unauthorized or malicious use.
  • Regular Security Reviews: Regularly reviewing the security of API keys is essential. Furthermore, organizations should take prompt corrective measures if they detect any security vulnerabilities. This is important to comply with current safety standards and to make continuous improvements.

How to Obtain and Use an API Key?

In this section, we will talk about how to obtain an API key and how to use it. We will obtain the API key from APILayer, which is the most popular API marketplace today, free of charge.

Discover how to list your own API under APILayer and get users from all over the world.

For this, we will obtain an API key from the numverify API on the APILayer’s homepage.

home page of the apilayer marketplace

For this, let’s click on the ‘NUMBER VERIFICATION API’ on the homepage and select the free plan from the subscription plans on the page that opens and press the ‘subscribe’ button. Then we will quickly register to APILayer from the pop-up that opens.

subscription plans of the numverify api

After registration, we will obtain an API key of the numverify API. Then, on the page that opens, click the ‘Live Demo’ button.

api keys page

APILayer offers its users a highly advanced API testing playground. With this playground, users can find integration codes for more than 90 APIs.

When we examine the JavaScript code on the playground screen that opens, we see that the API key is on the header part of the request. Let’s enter a sample phone number to test the numverify API with this API key. After entering the phone number, let’s press the ‘Run Code’ button. The response we get after pressing this button is as follows.

playground page of the apilayer marketplace

Learn more in our comprehensive documentation.


In conclusion, it is very important to consider the security of these APIs in every application that uses APIs. APIs can carry confidential and important information. However, without proper security measures, data in APIs can easily fall into the hands of malicious individuals. Therefore, one of the most common and effective methods for protecting APIs today is the use of an API key. With the API key, API owners can only open their data to the users they authorize.

Use our highly secure APIs by obtaining an API key, and get many unique advantages, including API usage information.


Q: How can I Differentiate the Purposes or Functionalities of Both API Keys in My Application?

A: To differentiate the purpose or functionality of both API (Application Programming Interface) keys, you can assign different roles or permissions to each key. For example, developers can use one API key for public data access or read-only operations, while another API key can provide more privileged access with the ability to modify or create data.

Q: What are the Key Responsibilities of an API Server in a Web Application Architecture?

A: The API server responsibilities play an important role in web application architecture. Here are the key functions of the API server:

  • Data Submission
  • Processing Client API Requests
  • Data Validation and Authorization
  • Business Logic Implementation
  • Error Management

Q: What are Some Use Cases for Using API Keys?

A: Almost every API today uses the API keys. There are several use cases for using API keys. Here are some examples:

  • User Authentication and Authorization
  • Project Authorization
  • Service Quotas and Limitations
  • Third-Party Integrations
  • Creating Revenue Model Based on API Request
  • Monitoring and Analyzing Every API Call

Q: What are the Benefits of Using an API Key for Developers?

A: There are many benefits to using API keys for developers. Firstly, API keys provide authentication and authorization, providing secure access to the API. It protects sensitive data. Moreover, API keys can be used to monitor API usage and enforce restrictions. So, it is possible to prevent unwanted or excessive use of API services.

Q: Do All API Products in APILayer Require API Keys?

A: Yes, they do. Certainly, developers must obtain an API key in order to utilize the 90+ unique API products listed in the APILayer. Notably, by making HTTP calls with a valid API key, users can effortlessly access and retrieve the desired data.

Related posts

The Best Free APIs to Use in 2024 for Your Business


App Store Search API: How To Optimize Your App's Visibility


What is an API? Understanding All the Key Factors


How To Rewrite And Enhance Any Article Using Paraphraser AI

Leave a Reply

Your email address will not be published. Required fields are marked *