What is an API Key?


A common question frequently arises when talking about application programming interface (API) is: What is an API key? APIs enable communication between software programs that would otherwise be incompatible and are the technology behind many strong integrations you use on a daily basis. An API key is a special identifier used to access or make an API call. Software applications send and receive data using APIs. They can link programs together so they can share functionality. 

What is an API Key?

An API key is required to connect to or communicate with another API. The API keys offer an initial step in securing cloud APIs. The API call begins with one API calling another, and then the API key is provided to get access. This process is similar to user authentication for web applications and mobile phones.

The API key indicates that the connecting API has a defined set of access rights and a “password” or key. For example, a program that transmits medical forms to patients would require a connection between its own API and a program that stores medical forms. An API key is given to the initial application by the owner of the medical forms API, and it can only be used to access medical forms.

Why Use an API Key?

API keys are frequently used to limit access to the API’s interface and track its usage. This is usually done as a precaution against misuse or malicious intent. The API verifies an entered API key against its client database before deciding whether to approve or reject a request based on the key. 

API owners also use API keys to keep track of API activity, including the kinds of queries made and how frequently they are made by specific customers. The API owners can filter by key and examine all requests from a specific client because each request has a corresponding key.

Common reasons to use an API key include the following:

Project Authorization 

Projects use API keys to authenticate a user and the project itself, providing security. API keys offer project authorisation through project identification. 

An API key can be used to identify a particular project or the application making the API call. While not as secure as the authentication tokens, API keys help identify the project or application making the call. This guarantees that they can also be used to assign usage data to a particular project and deny requests for inappropriate access.

API keys are frequently used to confirm that the application making the API call has permission to do so. The activation of the API being used in the project will also be verified during authorisation.

User Authentication

Authentication techniques are used to recognise the caller requesting API access. Endpoints or mobile devices can use the authentication token data to determine whether to authorise a request. The API server can use it to determine whether the user has permission to make the call.

User authentication ensures that the caller is who they say they are by confirming or verifying the user’s identity. User authorisation verifies if the caller has the right to make the specific request they made.

API keys cannot be used for:

  • Secure authorisation
  • Identifying individual users
  • Identifying the creator of a project

How to Use API Keys?

APIs usually demand that developers acquire a key before sending requests. The process should be explained in detail and include all the information you need to get started on the website of the API developer.

You will generally need to provide an email address and other details to register for a developer account. You will then be prompted to register your project and provide any information about it that the API owners should be aware of. At least one API key, a special string of randomly generated characters connected to your project, should be provided to you.

API keys are helpful when connecting programs to share data or to connect to other systems that supply the needed data without the need for coding. 

For example, there are a number of cloud-based APIs that customers can connect to use Amazon Web Services to manage back-end servers. Simple API connections are either free, like many services, or cost money and an agreement.

API usage is widespread and rising, particularly as device and application connectivity increases. For instance, Google Maps is widely used by almost all mobile and web applications to give location and address information. Without Google Maps, where would businesses that deliver meals be?

Government organisations, healthcare providers, and pretty much anywhere else where data sources can be shared securely have API connections. Currently, API connections allow healthcare organisations to share and exchange patient data. 

Are API Keys Secure?

Web APIs are usually the target of cyberattacks because they transmit sensitive data between apps over the internet, such as login passwords, personal information, and financial transactions. The APIs must be extremely secure in order to prevent this.

An API can identify a project and inform which resources it can access using API keys. However, experts do not believe that API keys alone are secure enough. This is due to several factors, including:

  • API keys cannot authorise the specific person making the call but only the project or application submitting the request. 
  • Similar to passwords, API keys are only useful if their owner saves them safely. A key can be easily misused if it ends up in the wrong hands.
  • Since API keys don’t usually expire, a hacker can use one for as long as they want without the key’s owner having to regenerate or deactivate it.

Popular APIs today also need user authentication and permission because of these reasons. User authentication verifies that the requester, rather than the application, is who they claim to be. Verifying the user’s authorisation shows they have the right to fulfil their request.

Authentication tokens, which are safer than API keys, are used to perform user authentication and authorisation. 

How to Securely Store API Keys?

API keys are still widely used and helpful for identifying calling projects in spite of their shortcomings. When interacting with an API, there’s a strong possibility you’ll need to keep track of one or more.

Like passwords, API keys work similarly and must be maintained and secured. Here are some fundamental actions you can take to reduce the chance of a key being stolen:

  • Don’t write your key anywhere that is accessible to the public, such as on a sticky note or in a file on a shared computer. 
  • When documenting your project, such as through screenshots, uploading to a public repository, or including it in a URL, take care not to reveal your key unintentionally.
  • Avoid writing your API key straight into your software because this will make it visible to everyone who has access to your source code.
  • Regenerate your API key and mark it as the latest shared key before distributing it.
  • Never send API keys through email.
  • Always utilise HTTPS/SSL when requesting information from an API; otherwise, certain APIs won’t process your request.
  • Give each project a unique API key, then label it properly. If you find one, you can regenerate or deactivate a compromised key without affecting your other projects.


API keys support the connections that keep people, things, and data connected.

A library of APIs is readily available to most software development companies, some of which are agreement-free and affordable. 

Learning to Code and APIs

As part of Code Institute’s Full Stack Software Development with Specializations programme, students learn how to interact with APIs. If you’re new to software development and want to learn some of the basics for free, then try our 5 Day Coding Challenge. After one hour a day over five days, you’ll have built your first web page. Register now through the form below.


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