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What is an API Key?

What is an API Key?

Harold Bell
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Key Takeaways

API keys are vital authentication tools for API clients, ensuring secure access to data and functions. They function like ID cards, granting access upon verification. Monitoring API activity through keys helps detect and mitigate security threats, such as malicious attacks or unauthorized access attempts. Regular updates and additional security measures improve overall API security, which is crucial for preventing breaches.

Knock, knock. Who’s there? API client. API client who? This little digital chat happens billions of times a day in the world of IT. As more companies undertake digital transformation initiatives, they are exposing more of their applications and data sources through application programming interfaces (APIs). Indeed, virtually all modern software applications rely on these standards-based interfaces to connect with user devices and other applications. For the sake of security and reliability, it is essential to grant API access only to API clients that can verify their identities. The API key makes this happen, allowing the API client to assert its identity.

An API key is a unique bit of code that identifies the API client to the API. It’s like an ID card. It might look something like this: e7062c5b-d95d-4fa5-af31-52cb6e662816. Any number of platforms can generate the keys. When the API client invokes the API, the API “asks” for the API key. Once the client presents the key, the API grants access. Most API keys are static. They remain in effect until they are revoked.

Why do you need an API Key?

API keys have two main purposes. One is authentication, a step that verifies that an API client is what it says it is. The API key signifies that the API client has permission to invoke the API. The process occurs at the API endpoint or API server.

The second purpose is authorization, which determines which API functions the API client is entitled to access. After all, an API may represent more than one function. And, it’s likely that not every API client will be authorized to use them all. One API client may get access to data set A, while another API client gets access to data sets A and B, and so forth. To realize this objective, the API project may assign more than one API key, with each key entitling the client to distinct access rights.

How do API keys work?

API keys work in a fairly straightforward “Show us your ID” process, sort of like going through the TSA checkpoint at the airport. When the API client requests access at the API endpoint, the API checks its client database for the key. If the key being presented matches the key in the database, the API client is allowed to access whatever data and functionality is made available through the API.

The owners of the API can also use the API key to monitor activity on the API. For example, they can track the number and types of requests being made, because each request links back to a specific API key. This capability has a useful security benefit, as well. If a malicious actor has stolen an API key, for example, then that key’s activities can provide evidence of an attack—potentially enabling API security tools to shut down access before the attack does any serious damage.

When should you use an API key?

The best uses for API keys occur in situations where the API owner wants to control API traffic. Requiring an API key obstructs traffic sources of unknown origin or questionable integrity. On a related note, API keys are useful when API owners want to monitor API traffic patterns. They might want to do this for security reasons, e.g., to detect malicious traffic or denial of service (DoS) attacks. Or, they may want to measure traffic to better understand how to optimize API performance or negotiate terms with API users.

Difference between API keys and account credentials

An API key is an identifier for the API client, but it differs from a set of API account credentials. The distinctions arise in several areas. For one thing, the API key identifies application requests, but not users on an individual basis. Indeed, there could be hundreds of end users who access an API through the same API client. The API key, on its own, cannot distinguish between them.

To address this limitation of access control, some APIs require users to create accounts. Though API user accounts vary in structure, they tend to resemble software user accounts. They might mandate that the user set up a unique username and password. The API account credentials might also include an authorization token, such as one based on OAuth standards. With API account credentials, the API owner can know exactly which end-user has accessed the API.

Keeping API keys secure

Given that the API key provides access to the API, and thus the data it represents, it should not be a surprise that hackers tend to be interested in stealing them. Getting ahold of an API key enables a malicious actor to breach data and systems fronted by the API. Or, they can abuse the key and flood the API with requests, disrupting business operations in the process. For these reasons, it is wise to devise and implement security controls that protect API keys.

For context, API key security should ideally be viewed as part of application security and data security. The API, after all, is the gateway to an application. If the API key is stolen, there will be very deficient application and data security.

Typical API key security countermeasures include:

  • Setting “rate limiting” controls, so even if an API key falls into the wrong hands, the attacker’s ability to access the API is constrained
  • Reviewing API permissions to avoid excessive or unnecessary grants of access privileges
  • Deploying threat/attack detection and response mechanisms that will catch abuse of API keys in the early stages of an attack
  • Updating API keys on a regular basis, which reduces the likelihood of old or neglected keys getting misused
  • Adding tokens to the user authentication process
  • Encrypting API requests and responses

Noname’s Recon solution offers users many of these capabilities. It has the ability to monitor APIs at runtime, detecting suspicious activity and alerting security managers of possible attacks. The solution also tracks API activity and traffic, with the goal of detecting and preventing breaches of the API, as well as theft of API keys.

API keys are identifiers that enable an API endpoint to authenticate an API client and limit its access according to authorization policies. They are not a complete API security solution, however, as they do not track individual end users. For better API security, it’s best to augment the API key with API account credentials, which may include tokens. API keys need to be protected, however, as they can be abused by hackers who are intent on breaching APIs.


How do I secure my API key to prevent unauthorized use?

To understand what an API key is and the importance of securing it, you must first grasp the meaning of APIs. Application Programming Interface is a set of rules and tools that allows different software applications to communicate and interact with each other. An API key is a code that provides authentication and authorization for accessing and using an API, acting as a secure identifier for the associated application or user.

Securing your API key is crucial to prevent unauthorized use and potential vulnerabilities. To minimize exposure, avoid embedding API keys in front-end code. Instead, use environment variables for a more secure storage solution. Implement access control methods like IP whitelists to restrict usage to trusted sources.

Embracing API security best practicesis essential for safeguarding your API keys and ensuring the integrity of your APIs. By following these measures, you enhance your system’s security posture and reduce the risk of unauthorized access to sensitive information through compromised API keys.

What should I do if my API key is compromised?

If your API key is compromised, take swift action to mitigate potential risks. Immediately revoke the compromised key and generate a new one to prevent unauthorized access. Review account activity thoroughly to identify any suspicious behavior. Enhance overall API security by regularly conducting security testing to identify vulnerabilities. By promptly responding to a compromised API key, you protect your system and data, ensuring a secure and resilient API infrastructure.

How many API keys can I generate for a single account?

The number of API keys you can generate for a single account varies by service provider. It’s advisable to consult the specific API’s documentation or support resources for precise details on key generation limits. Each service may have its own policies and considerations regarding API key management, so reviewing their guidelines ensures you adhere to their stipulations and maximize the functionality of your API keys within the specified limits.

How do I monitor the usage of my API key?

Effectively monitor your API key usage using dashboard tools provided by the API service. Review usage patterns regularly to identify anomalies, potential abuse, or unexpected charges. Proactive monitoring is crucial for maintaining the integrity and security of your API key. 

For comprehensive API key protection and monitoring, consider using Noname Security’s API security platform. Request a demo to explore how Noname enhances API security, ensuring robust monitoring and protection against potential vulnerabilities or unauthorized access to your APIs. Integrate advanced security measures to safeguard your API keys and maintain a secure digital ecosystem.

Harold Bell

Harold Bell was the Director of Content Marketing at Noname Security. He has over a decade of experience in the IT industry with leading organizations such as Cisco, Nutanix, and Rubrik, and has been featured as an executive ghostwriter in Forbes Technology Council and Hacker News.

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