API Security 101: Best Practices, How-to Guides, Checklist, FAQs

Note: This is our master guide on API Security where we solve common developer queries in detail with how-to guides, common examples and code snippets. Feel free to visit the smaller guides linked later in this article on topics such as authentication methods, rate limiting, API monitoring and more.

Today an average SaaS company today has 350 integrations. They rely heavily on APIs to share data and functionality, both internally and externally. This reliance has made the need for solid API security practices more crucial than ever. 

The consequences of overlooking API security are nothing short of disastrous, with the potential to expose sensitive data, compromise user privacy, and open the door to cyberattacks that can wreak havoc on an organization's operations.

In this article, we will dive into the world of API security —

  • The ever-evolving threats that surround APIs
  • Best practices to protects your APIs (detailed step-by-step guides for quick implementation)
  • Downloadable API security checklist
  • Answers to common FAQs asked by developers
  • And finally, we will show you how you can eliminate the risks altogether by adopting a new approach to API integration

Whether you're a developer creating APIs or dealing with their seamless integration, these practices will strengthen your infrastructure but also preserve the trust of your users and partners in an increasingly interconnected digital landscape.

So, let’s get started.

API Security Risks

Before diving deeper into the API security best practices, it's crucial to have a solid grasp of the risks and threats that APIs can face. These risks can stem from various sources, both external and internal, and being aware of them is the first step towards effective protection. 

Here are some of the key API security risks to consider:

  1. Unauthorized access
  2. Broken authentication tokens
  3. Injection attacks
  4. Data exposure
  5. Rate limiting and Denial of Service (DoS) attacks 
  6. Third party dependencies
  7. Human error
Read: Common Risks to API Security and their consequences where we discussed all these threats in detail

The old adage "prevention is better than cure" couldn't be more apt in the realm of API security, where a proactive approach is the key to averting devastating consequences for all parties involved.

Keeping this in mind, let’s dive deeper into our API security best practices.

API security best practices

Ensuring API security means providing a safe way for authentication, authorization, data transfer and more.

1. API Authentication and Authorization methods

API authentication and authorization methods are the most essential components of modern web and software development. These methods play a crucial role in ensuring the security and integrity of the data exchanged between systems and applications. 

Authentication verifies the identity of users or systems accessing an API, while authorization determines what actions or resources they are allowed to access. 

With a variety of techniques and protocols available, such as API keys, OAuth, and token-based systems, developers have the flexibility to choose the most suitable approach to protect their APIs and the data they manage.

Read our article on API Authentication Best Practices where we discuss top 5 authentication protocols such as OAuth, Bearer tokens, Basic auth, JWT and API keys in detail.

While choosing the right protocol depends on your specific use case and security requirements, here's a quick comparison of the 5 API authentication methods:

API authentication and authorization

Now, let’s explore how data can be transferred securely between API calls.

2. Secure data transmission: Encryption and HTTPS

When it comes to API security, ensuring that data is transmitted securely is an absolute must. 

Imagine your data is like a confidential letter traveling from sender to receiver through the postal service. Just as you'd want that letter to be sealed in an envelope to prevent prying eyes from seeing its contents, data encryption in transit ensures that the information exchanged between clients and servers is kept safe and confidential during its journey across the internet. 

HTTPS

The go-to method for achieving this security is HTTPS, which is like the secure postal service for your data. 

HTTPS uses Transport Layer Security (TLS) or its predecessor, Secure Sockets Layer (SSL), to encrypt data before it leaves the sender's location and decrypt it only when it reaches the intended recipient. 

Think of TLS/SSL certificates as the unique stamps on your sealed letter; they ensure that the data's journey is tamper-proof and that it's delivered only to the right address. 

So, whenever you see that little padlock icon in your browser's address bar, rest assured that your data is traveling securely, just like that confidential letter in its sealed envelope.

In a world where data breaches are a constant threat, secure data transmission is like the lock and key that keeps your digital communication safe from potential eavesdroppers.

Note: As an API aggregator, Knit, prioritizes user privacy and commit to keeping your data safe in the best way possible. All data at Knit is doubly encrypted at rest with AES 256 bit encryption and in transit with TLS 1.2. Plus, all PII and user credentials are encrypted with an additional layer of application security. Learn more about Knit's security practices here 

3. Input validation and parameter sanitization

In the world of API security, one area that often flies under the radar but is absolutely critical is input validation and parameter sanitization. It's like inspecting every ingredient that goes into a recipe; if you miss something harmful, the entire dish could turn out toxic.

First, let's talk about the risks. 

Input validation failures can open the door to a variety of malicious attacks, with one of the most notorious being injection attacks. 

These crafty attacks involve malicious code or data being injected into an API's input fields, exploiting vulnerabilities and wreaking havoc. Two common types are SQL injection and Cross-Site Scripting (XSS), both of which can lead to data breaches and system compromise. 

To learn more about injection vulnerabilities, read Common API Security Threats Developers Must Know About

How to defend against injection attacks 

Well, think of sanitizing user inputs as thoroughly washing your hands before handling food – it's a fundamental hygiene practice.

By rigorously examining and cleaning incoming data, we can block malicious code from getting through. For instance, when dealing with user-generated content, we should sanitize inputs to remove potentially harmful scripts or queries.

Additionally, for database queries, you should use parameterized statements instead of injecting user inputs directly into SQL queries. This way, even if an attacker tries a SQL injection, their input gets treated as data rather than executable code.

In the above example, we use a parameterized statement (? as a placeholder) to safely handle user input, preventing SQL injection by treating the input as data rather than executable SQL code.

In essence, input validation and parameter sanitization are like the gatekeepers of your API, filtering out the bad actors and ensuring the safety of your system. It's not just good practice; it's a crucial line of defense in the world of API security.

4. Rate limiting and Throttling

Both rate limiting and throttling are critical components of API security, as they help maintain the availability and performance of API services, protect them against abusive usage, and ensure a fair distribution of resources among clients. 

Rate limiting restricts the number of API requests a client can make within a specific timeframe (e.g. requests per second or minute) while throttling is a more flexible approach that slows down or delays the processing of requests from clients who exceeded their allotted rate limit instead of denying requests outright. 

Throttling is useful for ensuring a more graceful degradation of service and a smoother user experience when rate limits are exceeded. The exhaustion of rate limits are often denoted by HTTP error code 429.

These techniques are often implemented in combination with each other to create a comprehensive defense strategy for APIs.

Read: 10 API rate limiting best practices to deal with HTTP error code 429

5. API monitoring and logging

API monitoring and logging are vital for proactive security measures, threat detection, and incident response. 

API monitoring involves the continuous observation of API traffic and activities in real-time. It allows for immediate detection of unusual or suspicious behavior, such as spikes in traffic or unexpected access patterns. Beyond security, it also aids in optimizing performance by identifying bottlenecks, latency issues, or errors in API responses, ensuring smooth and efficient operation. 

API logging involves the recording of all API interactions and events over time. This creates a detailed historical record that can be invaluable for forensic analysis, compliance, and auditing. They are invaluable for debugging and troubleshooting, as they contain detailed information about API requests, responses, errors, and performance metrics. 

Monitoring and logging systems can also trigger alerts or notifications when predefined security thresholds are breached, enabling rapid incident response.

Access Logs and Issues in one page

This is exactly what Knit does. Along with allowing you access to data from 50+ APIs with a single unified API, it also completely takes care of API logging and monitoring. 

It offers a detailed Logs and Issues page that gives you a one page historical overview of all your webhooks and integrated accounts. It includes a number of API calls and provides necessary filters to choose your criterion. This helps you to always stay on top of user data and effectively manage your APIs.

API monitoring & logging

6. Regular security audits and Penetration Testing

Regular security audits and penetration testing are critical components of a comprehensive API security strategy. They help identify vulnerabilities, assess the effectiveness of existing security measures, and ensure that an API remains resilient to evolving threats.

  • Security audits involve a thorough review of an API's design, architecture, and implementation to identify security weaknesses, misconfigurations, and best practice violations, and assess whether an API adheres to security policies, standards, and regulatory requirements. This is also important for ensuring compliance with data protection laws and industry regulations.
  • Meanwhile Penetration testing, or pen testing, involves simulating cyberattacks to identify vulnerabilities, weaknesses, and potential entry points that malicious actors could exploit. It ​​attempt to exploit API vulnerabilities in a controlled environment to assess the API's resilience against real-world threats, including SQL injection, cross-site scripting (XSS), and more.

The results of penetration testing provide insights into the API's security posture, allowing organizations to prioritize and remediate high-risk vulnerabilities. Penetration tests should be conducted regularly, especially when changes or updates are made to the API, to ensure that security measures remain effective over time.

These practices are essential for safeguarding sensitive data and ensuring the trustworthiness of API-based services.

7. API lifecycle management and decommissioning

A comprehensive approach to API security involves not only establishing APIs securely but also systematically retiring and decommissioning them when they are no longer needed or viable. 

This process involves clearly documenting the API's purpose, usage, and dependencies from the outset to facilitate informed decisions during the decommissioning phase. Also, you should implement version control and deprecation policies, enabling a gradual transition for API consumers and regularly audit and monitor API usage and access controls to detect potential security risks. 

When decommissioning an API, the sunset plan should be communicated with stakeholders while providing ample notice, and assistance to the users in migrating to alternative APIs or solutions.

Finally, a thorough security assessment and testing should be conducted before decommissioning to identify and resolve any vulnerabilities, to ensure that the process is executed securely and without compromising data or system integrity.

Read: Developer's guide to API lifecycle management

8. Third-Party API Security Considerations

When integrating third-party APIs into your application, it's crucial to consider several important security factors. 

  • First and foremost, thoroughly review the reputation and trustworthiness of the API provider. Assess their security practices and history of vulnerabilities. 
  • Additionally, scrutinize the permissions and access levels you grant to the third-party API. Only provide the minimum access necessary for your application to function to limit potential risks. 
  • Monitor the API's security updates and patch management, as vulnerabilities may emerge over time.
  • Ensure that data transmitted between your application and the third-party API is encrypted and protected to safeguard against interception or tampering. 
  • Lastly, have contingency plans in place for potential downtime or security breaches in the third-party API, which might affect your application's availability and data security.
Read: How to evaluate security before choosing a third-party API provider

API security checklist

To sum up everything that we discussed above, here is a checklist that provides a comprehensive overview of critical aspects to consider when securing your APIs, from authentication and authorization to encryption, monitoring, and incident response.
Although, you’ll need to tailor it to your specific needs and regularly review and update it to adapt to evolving security threats and best practices.

To download checklist, click here

Common API security FAQs by developers

We have a separate post to deal with all your day-to-day API security FAQs where we discuss the following and more:

1. How to handle when a token expires – generate and store new?

2. How often should I perform security audits and testing for my APIs?

3. What should I do in case of a security breach involving my API?

4. How can I monitor and log API activity for security purposes?

Read all the FAQs

Enable maximum security for your API integrations with Knit

If you are dealing with a large number of API integrations and looking for smarter solutions, check out unified API solutions like Knit. Knit ensures that you have access to high quality data faster in the safest way possible.

  • Knit is the only unified API in the market that does NOT store a copy of your end user data in its servers or share it with any third party. All of our syncs are event-based and happen via webhooks to ensure that your data is not subjected to any external threats during the transfer. Learn more about Knit's secure data sync here
  • Knit complies with industry best practices and security standards. We are SOC2, GDPR and ISO27001 certified and always in the process of adding more security badges to our collection.
  • We monitor Knit's infrastructure continuously with the finest intrusion detection systems. Plus, our super responsive support team is available 24*7 across all time zones to make sure if at all a security issue occurs, it is resolved immediately.
We understand how crucial your data is. That's why we are always fine-tuning our security measures to offer maximum protection for your user data.  Talk to one of our experts to learn more. If you are ready to build integrations at scale, get your API keys for free

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