Job · Appnovation
Octopus Payment Gateway Microservice
Standalone multi-tenant payment gateway service with HMAC-SHA256 signing, JWT authentication, and merchant management system.
- Role
- Platform & DevSecOps Engineer
- Type
- Built in my full-time job at Appnovation
- Period
- Sep 2025 to Oct 2025
Architected and developed a production-ready payment gateway microservice that extracts and generalizes payment processing logic into a reusable service. Features comprehensive security infrastructure including APIP-compliant authentication, AES-256-GCM encryption, and automated webhook delivery with retry logic.
What I built
- 01Designed and implemented complete cryptographic service with SHA-256 hashing and AES-256-GCM encryption
- 02Built HMAC-SHA256 request signature system with replay attack prevention
- 03Created merchant management APIs with key rotation and profile management
- 04Implemented async webhook delivery system with retry logic and failure handling
- 05Developed comprehensive test suite with unit and integration tests
Stories worth telling
Contributed 3,680+ lines of production code in 2 weeks
APIP-compliant multi-tenant architecture
Automatic API key rotation with graceful expiration
Production-ready with complete security infrastructure
Numbers
- 3,680+ lines of code
- Multi-tenant architecture
- APIP compliant
Stack
- Java 17
- Spring Boot
- Spring Security
- PostgreSQL
- Docker
- JWT
- HMAC-SHA256
- AES-256-GCM