As a Java developer with expertise in Spring and API development, I specialize in building scalable and robust API middleware. 

Some of the core features I can implement are:

• Adhering to the industry standards for API development like Open Banking Standards and REST standards
• Message level security for sensitive personal information with industry standard cryptography
• Mitigating top 10 OWASP API vulnerabilities
• Highly scalable and fault tolerant APIs
• Implementation of Redis/Caffeine/Infinispan cache
• Custom 3rd party integrations like with any payment gateway (Ex- Stripe, BillDesk etc)
• Auditing framework with Apache Kafka or RabbitMQ 
• Logging and Traceability framework
• Centralized exception handling
• Batch Processing
• OAuth implementation
• JWT tokens 
•  Enabling HTTPS
• Entitlement framework
• Consultation around overall architecture of your application