APIs play a crucial role in connecting apps, services, and third-party platforms. They are freely accessible to everyone, making them an easy target for cyber risks such as illegal access, data breaches, and denial of service attacks. A single vulnerability can expose sensitive information, disrupt operations, and cause compliance concerns.

Securing an API needs an extensive strategy that includes strong authentication, access controls, secure data management, and ongoing monitoring. To protect their APIs from illegal activity, organizations should use encryption, rate limiting, and threat monitoring.

Using a complete security checklist can help to reduce risks, secure user data, and protect APIs from new threats. This blog explores the top 10 API security checklists to protect organizations’ APIs.

Authentication & Authorization

APIs should have strong authentication and authorization to prevent unauthorized access. Use OAuth 2.0, OpenID Connect, and mutual TLS to ensure only validated users and services can connect with the API. Attribute-based access control (ABAC) or Role-based access control (RBAC) allows flexible authorization management. Use multi-factor authentication (MFA) to increase security for essential endpoints. Ensure that tokens and credentials are invisible in URLs. Short token lifespans and regular key rotation will reduce the possibility of misuse.

Input Validation and Data Security

Invalidated input increases the risk of injection attacks and data leaks. Enforce strong schema validation to ensure that the system processes only accurate structured input. Input sanitization helps to remove possibly malicious payloads before execution, while output encoding prevents cross-site scripting (XSS). Transport Layer Security (TLS 1.2+) encrypts data during transmission to prevent theft and modification.

Usage of strong encryption helps in protecting data from unapproved access. Ensure that APIs only return the required data and reduce the exposure of internal information. Proper error handling will help to stop attackers from getting insights into system behavior.

Rate Limiting & Throttling

If organizations do not control request volumes, APIs become vulnerable to brute-force attacks and denial-of-service (DoS) situations. Set rate limitations per user IP or token to avoid excessive API consumption. Use throttling methods to reduce repeated requests and ensure fair resource allocation. Continuous backoff in retry logic reduces system overload during failures.

Real-time traffic monitoring will help to find abnormalities and misused patterns. Implement automated blocking methods to reduce threats before they enter the system. Failed login attempts and excessive requests will help to find attack patterns.

Logging and Monitoring

Continuous logging and monitoring will provide visibility into API activity and security events. Security Information and Event Management systems enable security teams to find abnormalities and give notifications for malicious behavior. Keep logs secure and check them regularly to find threats like several failed login attempts or unusual traffic surges. Proper alerting mechanisms will enable security teams to respond to incidents quickly, and API analytics will help track usage trends and associated security threats.

API Endpoint Security

Exposed API endpoints are popular attack vectors that organizations must protect. HTTPS ensures encrypted communication between clients and servers to prevent theft. Restrict unnecessary HTTP methods such as TRACE and ensure that methods like PUT and DELETE require proper authentication and authorization to prevent unauthorized modifications. Cross-Origin Resource Sharing (CORS) policies, when properly configured, prevent unwanted cross-domain queries.

Use Web Application Firewall (WAF) filters to find unsafe traffic before it reaches APIs. Endpoint access restrictions based on IP whitelisting or authentication tokens reduce unwanted user exposure. Regular security evaluations will help to find misconfigurations and weaknesses in API endpoints.

Secure API Keys & Secrets

Hardcoding secrets in programs or exposing them in version control systems will increase security risks. Keep API keys, tokens, and other sensitive credentials secure. Use secret management systems such as AWS Secrets Manager, HashiCorp Vault, and Azure Key Vault for secure storage.

Regular key rotation reduces the impact of identity theft. Give fewer permissions to API keys to execute their intended function and transfer data securely via encrypted channels to prevent theft. Monitoring and auditing API key usage will help to find unauthorized access attacks.

Security Testing & Audits

Regular security testing will help to find and reduce API risks before attackers exploit them. Use automated tools to find misconfigurations, injection attacks, and insecure authentication. Security teams should perform pen testing to imitate real-world attack situations. The static and dynamic analysis of API code will help to find vulnerabilities during development.

Use dependency scanning to find security vulnerabilities in third-party libraries and frameworks and perform security audits to ensure that internal policies and regulations are followed. Continuous testing will help to maintain API security when new threats develop.

API Versioning and Inventory Management

Managing API versions will reduce the likelihood of old or vulnerable endpoints remaining in use and maintain an API inventory for visibility in all current endpoints and their versions. Remove outdated API versions to ensure that outdated implementations do not pose security vulnerabilities. Use versioning standards to specify a defined lifespan for each API, ensuring regular updates and patches.

Monitor API usage to detect irregular access patterns. Proper documentation supports the use of continuous security measures in API versions and a centralized API management solution to increase governance and security enforcement.

Third-Party API Security

API integration with third-party services will pose new risks so verifying third-party providers' security measures will reduce the risk of supply chain threats. Use only trusted sources to get API access, to prevent unauthorized interactions. Checking incoming data from third-party APIs ensures that it meets security and regulatory requirements.

Monitoring third-party API interactions will help in identifying vulnerabilities and ensuring continuous security compliance. Security agreements with third-party vendors should include strict security and data protection requirements. Perform ongoing testing of external APIs to avoid security breaches caused by insecure integrations.

Implementing an API Gateway

An API gateway is a centralized management layer that manages authentication, authorization, and traffic control. It uses rate limits, request validation, security policies for all APIs, and TLS termination at the gateway to ensure a secure connection between clients and backend services.

API gateways can integrate or include Web Application Firewalls (WAFs) to mitigate security threats. Standardized security enforcement across all APIs improves management while reducing security risks. Setting up an API gateway will improve security, scalability, and operational efficiency.

Final thoughts

API security is a process that needs monitoring, testing, and enhancements. Organizations will need strong authentication, access controls, encryption, and regular audits to protect their APIs and vulnerabilities before attackers exploit them. Real-time monitoring allows security teams to find and respond to possible threats. Security tools such as API gateways, WAFs, and automated scanning solutions help strengthen API protection while ensuring compliance with industry standards.

Akto provides real-time API security monitoring, automated vulnerability detection, and compliance regulation, which allows security teams to find threats early and prevent breaches without delaying development. Schedule a demo today to discover how Akto can improve an organization's API security.