API protection refers to the activities, tooling and practices involved in securing application programming interfaces (APIs). The goal of API protection is to secure APIs against cyberattacks, breaches and any unauthorized or unwanted use.
Because APIs are so common and enable access to sensitive software functions and data, they are becoming an increasingly desired target for attackers. This makes API protection a critical component of modern web application security.
API security is essential for protecting sensitive data like financial information or personal data, and preventing attacks that could compromise the integrity of the API and the systems it connects to.
Why is API protection important?
APIs enable businesses to integrate different systems and technologies: they function as a way for various applications to ‘communicate’ quickly. APIs often handle authentication tokens, personal data, payment information and a number of other highly sensitive activities. This makes them an attractive target for bad actors.
Since APIs are highly automated and predictable, this makes them an easier target for attackers to study and exploit. Attackers have been known to exploit API vulnerabilities to gain access to sensitive data or inject malicious code into applications, leading to data breaches, system crashes, and other serious consequences.
For these reasons, it is important to prioritize API protection tooling and strategies. Without proper protections in place, APIs can pose great risk to the business, its IP, and its brand and reputation.
What are the impacts of failing to use API protection?
Failure to implement robust API protection tooling and practices can result in several negative impacts to your business:
Data breaches and regulatory violations
Account takeover and credential abuse
Unauthorized access to sensitive resources
Business logic abuse
Service degradation caused by automated abuse
Resulting impacts to brand reputation and revenue from successful attacks
What risks can API protection defend against?
The OWASP Top 10 tracks the top API security risks and updates them every few years. This is a great starting place to reference and ensure your APIs are protected.
From this list, OWASP names the following as top API concerns:
Broken Object Level Authorization: OWASP states, “APIs tend to expose endpoints that handle object identifiers, creating a wide attack surface of Object Level Access Control issues. Object level authorization checks should be considered in every function that accesses a data source using an ID from the user”.
Broken Authentication: OWASP states, “Authentication mechanisms are often implemented incorrectly, allowing attackers to compromise authentication tokens or to exploit implementation flaws to assume other user's identities temporarily or permanently. Compromising a system's ability to identify the client/user, compromises API security overall.”
Broken Object Property Level Authorization: OWASP states, “Focusing on the root cause of authorization issues: the lack of or improper authorization validation at the object property level. This leads to information exposure or manipulation by unauthorized parties.”
Unrestricted Resource Consumption: OWASP states, “Satisfying API requests requires resources such as network bandwidth, CPU, memory, and storage. Other resources such as emails/SMS/phone calls or biometrics validation are made available by service providers via API integrations, and paid for per request. Successful attacks can lead to Denial of Service or an increase of operational costs.”
Broken Function Level Authorization: OWASP states, “Complex access control policies with different hierarchies, groups, and roles, and an unclear separation between administrative and regular functions, tend to lead to authorization flaws. By exploiting these issues, attackers can gain access to other users’ resources and/or administrative functions.”
Unrestricted Access to Sensitive Business Flows: OWASP states, “APIs vulnerable to this risk expose a business flow - such as buying a ticket, or posting a comment - without compensating for how the functionality could harm the business if used excessively in an automated manner. This doesn't necessarily come from implementation bugs.”
Server Side Request Forgery: OWASP states, “Server-Side Request Forgery (SSRF) flaws can occur when an API is fetching a remote resource without validating the user-supplied URI. This enables an attacker to coerce the application to send a crafted request to an unexpected destination, even when protected by a firewall or a VPN.”
Security Misconfiguration:OWASP states, “APIs and the systems supporting them typically contain complex configurations, meant to make the APIs more customizable. Software and DevOps engineers can miss these configurations, or don't follow security best practices when it comes to configuration, opening the door for different types of attacks”
Improper Inventory Management: OWASP states, “APIs tend to expose more endpoints than traditional web applications, making proper and updated documentation highly important. A proper inventory of hosts and deployed API versions also are important to mitigate issues such as deprecated API versions and exposed debug endpoints.”
Unsafe Consumption of APIs: OWASP states, “Developers tend to trust data received from third-party APIs more than user input, and so tend to adopt weaker security standards. In order to compromise APIs, attackers go after integrated third-party services instead of trying to compromise the target API directly.”
Aside from this list, you should also always be concerned about:
Shadow APIs: These are APIs that are not sufficiently secured but still used within a business. This usually happens when APIs are used or created in one part of a business and the security team isn’t aware of them, and therefore isn’t able to adequately secure them.
Injection attacks: When APIs accept input without proper validation. This enables attackers to slip malicious requests into an application and wreak havoc.
What are API protection best practices?
Aside from investing in strong API security tooling, there are several best practices you can follow to help keep your APIs secure.
Design and development
Follow secure API design standards (least privilege, schema validation)
Define authentication, authorization, and rate-limiting requirements early
Document endpoints and expected behavior clearly
Authentication and authorization testing
Test token expiration, revocation, and replay protection
Verify role-based and scope-based access controls
Attempt unauthorized access to protected resources
Input and schema validation
Test malformed requests, oversized payloads, and unexpected data types
Validate strict schema enforcement
Test for injection vulnerabilities
API testing
Simulate credential stuffing, enumeration, and scraping
Test rate limits and throttling behavior
Validate bot and anomaly detection effectiveness
Business logic testing
Attempt workflow manipulation to identify any weaknesses
Test edge cases and unexpected order of operations
Practice encryption
You should always ensure that data traveling via APIs is encrypted.
Who needs API protection?
In short, anyone or any business who uses APIs as part of their business ecosystem needs to ensure they have API protection strategies and tooling in place.
The more sensitive the data your APIs touch, though, the greater the need for robust API protection. Those particularly in need of API protection are:
Financial services industry: This is an obvious one. Financial institutions and fintech businesses need API protection both from a compliance requirement (think PCI DSS) and from a trust and security perspective. They touch the most sensitive data and require security solutions that reflect that.
Healthcare industry: Similar to financial data, health data is equally sensitive. Regulations like HIPAA require strong security practices, as do customers.
Retail and e-commerce industries: APIs are foundational to these businesses, helping with inventory, website ‘check out’ functionality, and shipping. Weaknesses here result in lost business trust and resulting revenue losses.
How Fastly can help
API security testing should be an ongoing effort. By combining secure design, continuous automated testing, manual validation, bot-aware abuse testing, and edge-based protection, organizations can significantly reduce the risk of API exploitation while maintaining performance and scalability.
Fastly API Securitygives y ou the full picture of your API landscape. You can understand what exists, gain confidence that things are working as expected, and make targeted API abuse mitigation decisions across the Fastly platform.
Fastly’s Edge Cloud Platform inspects and filters API requests at its globally distributed edge locations. This means malicious or abusive traffic like bot-driven attacks, credential stuffing, or API scraping can be blocked or throttled before it ever reaches your application servers. Stopping threats early reduces backend load, lowers latency, and limits blast radius during attacks.