5 Best Practices for
Building Resilient APIs
in 2025

APIs are the digital backbone of modern enterprises, enabling seamless integrations, data exchanges, and customer interactions. However, as API adoption grows, so does the risk of security breaches. Incidents like the breach in 2021 that exposed millions of user records and another in 2022 where financial data was compromised underscore the urgent need for resilient APIs.

Building resilient APIs requires more than just secure coding practices—it demands robust observability, real-time threat detection, and proactive vulnerability management. Rakuten SixthSense’s API Security platform offers cutting-edge solutions to ensure API resilience while addressing compliance and operational needs. Here are five best practices to build APIs that can withstand the challenges of 2025.

1. Implement Real-Time API Monitoring

Real-time monitoring is critical for detecting and mitigating security threats before they cause significant damage. It ensures continuous visibility into API traffic, helping identify anomalies and malicious activities.

Rakuten SixthSense Solution:

• AI-Driven Traffic Monitoring: Differentiates between legitimate traffic and malicious requests.
• Dynamic Rate Limiting: Prevents DDoS attacks and traffic overloads.
• Comprehensive API Discovery: Identifies shadow and zombie APIs that may introduce vulnerabilities.

In 2021, a breach exploiting unsecured APIs resulted in millions of user records being accessed. Real-time monitoring could have flagged unauthorized access attempts and mitigated the breach early.

2. Prioritize API Vulnerability Management

Unpatched vulnerabilities, misconfigurations, and outdated APIs are common entry points for attackers. Regular vulnerability assessments and proactive patching are essential to maintain a secure API ecosystem.

Rakuten SixthSense Solution:

• OWASP Top 10 Vulnerability Scanning: Identifies risks like broken authentication and injection flaws.
• Virtual Patching: Applies fixes instantly to reduce response times.
• Risk-Based Prioritization: Focuses on high-impact vulnerabilities to allocate resources effectively.

In 2022, attackers exploited vulnerabilities in APIs to gain unauthorized access to sensitive customer data. With Rakuten SixthSense’s vulnerability scanning and real-time patching, such risks could have been detected and resolved preemptively.

3. Enforce Strong Authentication and Authorization

API endpoints often handle sensitive data, making them attractive targets for unauthorized access. Implementing robust authentication and authorization mechanisms ensures only trusted users and applications can access your APIs.

Rakuten SixthSense Solution:

• Role-Based Access Controls (RBAC): Enforces granular permissions for API users.
• API Gateway Security: Protects endpoints by validating and securing requests.
• Sensitive Data Flow Monitoring: Tracks Personally Identifiable Information (PII) to prevent exposure.

In one case, an exposed API endpoint without authentication led to the compromise of sensitive data. Strong authentication protocols could have prevented such an incident.

4. Design for Scalability and Resilience

With APIs becoming critical for cloud-native applications, they must be designed to handle high traffic volumes without performance degradation. A resilient API should scale seamlessly to meet demand while maintaining robust security.

Rakuten SixthSense Solution:

• Dynamic Observability Dashboard: Provides real-time performance insights to optimize API efficiency.
• Scalable Threat Detection: Adapts to traffic surges, ensuring consistent protection.
• Hybrid and Multi-Cloud Support: Monitors APIs across AWS, Azure, and other cloud platforms.

An incident involving service downtime during a peak shopping event highlighted the importance of scalability. Rakuten SixthSense’s dynamic rate limiting and scalability features could have ensured continuous service availability.

5. Adopt Proactive Threat Detection with AI

AI-driven analytics enhance the ability to identify and respond to emerging threats. Proactive threat detection goes beyond traditional monitoring by predicting potential risks based on historical patterns.

Rakuten SixthSense Solution:

• Behavioral Analytics: Identifies unusual API usage patterns to detect advanced threats.
• Anomaly Detection: Flags suspicious activities in real time.
• Automated Responses: Executes predefined actions like attack blocking and rate limiting to mitigate threats.

In another example, attackers accessed API keys used for third-party integrations. Rakuten SixthSense’s behavioral analytics could have detected the unusual activity early, preventing significant financial losses.

Lessons from API Breaches

• Exposed API Keys: In 2022, attackers accessed exposed API keys, leading to significant financial losses. Automated API key management could have prevented this.
• Misconfigured Endpoints: A misconfigured API endpoint exposed sensitive customer data. Rakuten SixthSense’s configuration audits and real-time monitoring would have identified and secured the endpoint.
• Data Leaks from Unsecured APIs: A breach caused by an unsecured API exposed millions of user records. Real-time PII monitoring would have ensured data integrity and compliance.

Future Trends in Building Resilient APIs

• Zero-Trust Architecture: Verifies every API interaction to prevent unauthorized access.
• AI/ML in API Security: Enhances threat detection and response with machine learning models.
• Blockchain for API Logging: Ensures tamper-proof logs for auditability and transparency.
• Observability in Microservices: Provides comprehensive visibility into distributed API systems.

Building resilient APIs in 2025 demands a proactive approach to security, scalability, and observability. By implementing real-time monitoring, prioritizing vulnerabilities, enforcing strong authentication, designing for scalability, and leveraging AI-driven analytics, organizations can safeguard their API ecosystems.

Rakuten SixthSense API Security offers a comprehensive platform to address these challenges, combining advanced monitoring, threat detection, and compliance tools. With a proven track record of securing millions of API calls across industries like finance, healthcare, and e-commerce, Rakuten SixthSense empowers businesses to build APIs that are both resilient and secure.

Ready to future-proof your APIs? Discover how Rakuten SixthSense API Security can help you build resilient APIs for 2025 and beyond.