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What Are API Keys And How to Use Them?

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Organizations today increasingly rely on APIs (application programming interfaces). And rightly so. APIs have emerged as a business-enabling technology that allows organizations to create robust enterprise and consumer applications, get access to real-time data and information, and interconnect various layers of IT infrastructure. As APIs are quickly becoming one of the essential keys to digital transformation, it’s getting more important to be knowledgeable about different aspects of API utilization and management. One crucial aspect associated with APIs is API keys. But what are API keys? 

In this article, we’ll provide a thorough understanding of API keys and discuss why they are so important. 

What are API keys? 

API key

An API key is a unique identifier used to authenticate requests to an application programming interface (API). Since an API key serves as a unique identifier and provides a secret token for authentication purposes, every user has a specific API key. 

API keys are also used to control and track how the API is being used. 

It is possible to assign API keys with different access rights depending on what kind of project or user is trying to access it. 

API keys look like long strings of randomly generated characters. This code is passed between an API and its caller, allowing the system behind the API to identify the application making the call, the provider of the code, and the end-user. 

An example of an API that makes use of API keys is ipstack geolocation api. To make a successful request to this geolocation API, we need to pass our unique API key to the API’s endpoint:

What is the Purpose of API keys?

How to use API keys

API keys are used for various purposes:

API Keys for User Identification

An API key allow websites and applications to identify the user requesting access to an API. The user’s authorization token is checked to confirm the permission to make the call and authorize the request. 

When it comes to user identification, API keys are mainly used for two purposes: 

  • User authentication: API keys help verify the identity of the client making the API request. When an application sends a request to an API, the API key confirms that the request is coming from a trusted source.
  • User authorization: API keys can be used to control access to different parts of the API. By validating the API key, the API can ensure that the client has permission to perform the requested actions.

API Keys for Project Identification

Just like user authentication, API keys are widely used to identify and authorize software projects that are making calls to APIs. 

  • Project authentication: Identify a specific project that makes the call. 
  • Project authorization: Confirm that the project making the call has the right to access the API and all the necessary permissions for requested features or data. 

Usage Tracking

API keys also allow developers/service providers to track API usage. This is important for monitoring and managing how the API is used. This includes

  • Tracking the number of requests
  • Identifying usage patterns
  • Detecting potential abuse.

Rate Limiting

With API keys, service providers can enforce rate limits. This way, they can control how many requests a client can make within a certain timeframe. This helps prevent overuse or abuse of the API.

Blocking Unauthorized Traffic. 

API keys can be utilized to detect and block unauthorized and/or anonymous traffic, which may be an indicator of a hacker attack or other kind of malicious activity. 

How Do API Keys Work?

When a client application wants to access an API, it includes the API key in its request, typically in the HTTP headers, query parameters, or request body. The API server then validates the key to determine if the request should be allowed. Here’s a simple example of how an API key might be used in API requests:

In the above API request, we’ve made an API call to the ipstack API to fetch location data associated with the given IP address. The API key (access_key = YOUR_ACCESS_KEY) is used to authenticate with the ipstack API.

How Secure are API keys? 

are API keys secure

APIs are widely used across various IT systems and software layers, transmitting the personal data of users. Thus, it’s crucial to address API security seriously. Vulnerabilities in APIs can be exploited by hackers to steal sensitive information and get access to networks and IT systems. With the growing popularity of APIs, the frequency of such cyberattacks is also on the rise. 

While API keys are useful for authentication, they have some security limitations. Since API keys are typically provided to multiple users and projects, it is relatively easy for cybercriminals to steal an API key, which usually has no expiration date, allowing hackers to use it as long as they want unless the rightful owner generates a new key. 

API keys are vulnerable to various types of attacks. These include distributed denial-of-service (DDoS), broken access control, injection, and man-in-the-middle (MITM) attacks. Thus, it’s essential to project API keys.

Moreover, when it comes to API security, API keys should be complemented by other security mechanisms. To enhance security, API keys are often used in combination with other authentication methods, such as OAuth tokens, which provide more robust security mechanisms.

API Keys: Best Practices

  • Keep your API keys secret. Never expose them in client-side code or public repositories.
  • Store your API key securely on your server side.
  • Regenerate your API key regularly. This helps minimize the risk of unauthorized access if your key is compromised.
  • Limit the use of API keys to specific IP addresses, referrer URLs, or applications to reduce the risk of misuse.
  • Regularly monitor the usage of your API keys to detect any unusual activity that might indicate a security breach.

What are the Business Benefits of Using API keys? 

API keys can provide business benefits in a number of ways.

First of all, they serve as a key instrument to make sure that all the connections to APIs utilized in your IT systems and services are made by authorized users. Secondly, they can help you to gather valuable data to make sure all the components of your system are functioning in the intended way, and both customers and internal users can access the features and information they need.

Finally, an API key is a tool to control the usage of your systems and services by making sure specific users have the authorized level of access, meaning that they can only do and see what they are allowed to. 

Utilizing only high-quality professional APIs is the best way to gain maximum benefit from this technology. Apilayer is a platform that offers a set of APIs that allow organizations to easily automate multiple processes, such as online audience and user journey control, data conversion, user info verification, and real-time third-party data access.

For example, Ipstack is a scalable IP address geolocation and reverse IP lookup REST API. It allows users to utilize IP intelligence data to take control of their online audience, enhance user experience and prevent fraud efficiently.


API keys are a crucial component of APIs. They help ensure that only authorized clients can access and interact with the API, thus safeguarding data and services. Despite their simplicity, API keys offer significant advantages, including usage tracking, rate limiting, and integration with billing systems.

However, it’s essential to be aware of their limitations and potential security vulnerabilities. Best practices, such as keeping keys confidential, regularly regenerating them, and restricting their usage, are crucial to maintaining their effectiveness and ensuring the security of the systems they protect


What is in an API key?

An API key typically consists of a unique string of characters generated by the API provider. API keys play a crucial role in authenticating requests to an application programming interface (API).

Is the API key free?

It depends on the API you’re using. Some APIs offer a free plan with a free API key along with paid plans. For paid subscription plans, you need to get a paid API key. 

What is the difference between API and API key?

An API is essentially a set of rules/protocols that allows one software application to interact with another. An API key typically consists of a unique string of characters used to authenticate requests made to an API.

What is an api key used for?

API keys can be used as authentication tokens to authenticate requests made to an API.

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