I’m Mohsen Mohammadi, a Java engineer and team lead at a fintech company, specializing in payment gateway systems and backend engineering.

What I Do

I build and maintain payment processing infrastructure using:

  • Java & Spring Boot for backend services
  • Keycloak for authentication and authorization
  • MySQL & PostgreSQL for data persistence
  • Observability tools (monitoring, logging, tracing)

My focus is on building scalable, reliable systems that handle real money and real transactions.

What I Write About

Coffee Coded is my space for documenting:

  • Technical insights: Spring Boot patterns, backend architecture, payment system design
  • Production lessons: What works, what breaks, and how to fix it
  • Language learning: My journey with German and French (TCF exam preparation)

The posts here are written for me first — documenting solutions, crystallizing understanding, building reference material. If they help you too, that’s a bonus.

Get in Touch

Whether you want to discuss payment systems, Spring Boot best practices, or language learning strategies, feel free to reach out.