Back End Developer

About the role

We are looking for a Senior Backend Developer who can lead the backend part of our projects. You will design and

build the APIs our mobile app uses, guide other backend developers, and work closely with our mobile developers to

deliver features end to end. You stay hands-on with Java / Spring Boot every day.

Key responsibilities

• Lead backend development for features and releases: design, task breakdown, estimates and delivery.
• Design and build APIs for the mobile app (Java / Spring Boot), including the backend-for-frontend layer.
• Agree API contracts (OpenAPI) with mobile developers before build starts, so both sides can work in parallel.
• Work with mobile developers day to day: define response and error formats, provide mock APIs, and debug issues
• across app and backend together.
• Keep APIs backward compatible, so older app versions still work after a backend release.
• Review code and designs from other backend developers, and help them grow.
• Make sure APIs are secure (authentication, authorization, no sensitive data in logs) and fast enough for mobile
• users.
• Work with Product, BAs, Solution Architects and QA to turn requirements into technical designs.
• Support production issues and fix root causes.

Qualifications

• Strong experience in backend development, with experience leading the backend part of a project or a small team.
• Strong Java (17+) and Spring Boot (Web / WebFlux, Data, Security).
• Experience building REST APIs used by mobile apps (iOS, Android or Flutter), and working closely with mobile
• developers.
• Good API design: OpenAPI contracts, versioning, error handling, pagination and backward compatibility.
• Knowledge of API security: OAuth 2.0 / OpenID Connect, JWT and OWASP Top 10.
• Relational databases (PostgreSQL, Oracle or MySQL) and Redis caching.
• Microservices, resilience patterns (timeouts, retries, circuit breakers) and logging / monitoring.
• Testing with JUnit and Mockito. Git, CI/CD and Docker / Kubernetes.
• Good communication in Thai and English. Able to explain technical trade-offs clearly.

Nice to have

• Experience in banking, payments, cards, lending or fintech.
• Basic understanding of mobile development (Flutter, iOS or Android) and app release cycles.
• API gateways (e.g. Kong), Kafka or other messaging, and cloud platforms (AWS / Azure / GCP).
• Experience fixing VA / penetration-test findings.
• Knowledge of PDPA and Bank of Thailand IT regulations.
• Experience using AI coding assistants in a team.