Kotlin/Java Developer (Merchant Response)

Stack

Responsibilities

• ▹Develop new payment features and services
• ▹Design and implement external and internal APIs
• ▹Create and maintain processes in Camunda
• ▹Participate in designing and developing high-load system architectures
• ▹Support and enhance existing solutions and services
• ▹Write high-quality, test-covered code (unit and integration tests)
• ▹Conduct code reviews
• ▹Optimize system performance and database queries
• ▹Analyze and resolve production incidents and bugs
• ▹Analyze external providers' documentation and define epics and tasks based on proof-of-concept work
• ▹Collaborate with the QA team to ensure product quality
• ▹Maintain technical documentation and write technical specifications
• ▹Assist in onboarding new developers and ensuring code quality
• ▹Define technical and business epics, estimate tasks and participate in sprint planning

Requirements

• ▹3+ years of commercial development experience with Kotlin
• ▹Experience with the Spring Framework
• ▹Experience developing payment solutions (billing, payment gateways, processors, exchanges)
• ▹Practical experience integrating with external providers
• ▹Experience designing and optimizing relational databases (MySQL)
• ▹Experience with NoSQL databases (Redis)
• ▹Practical experience using AI-assisted coding tools (Claude, Codex, ChatGPT, Codeium, etc.)
• ▹Ability to critically review AI-generated code for production-ready quality
• ▹Knowledge of Event-Driven Architecture principles and distributed messaging systems (e.g. Apache Kafka)
• ▹Strong command of software development and design principles, TDD and CI/CD processes
• ▹Strong understanding of microservice architecture

About the company

The team builds a payment gateway that accepts funds from users on behalf of merchants and sends funds from merchants to users. The system stores user payment data and is subject to PCI DSS compliance, with multiple integrations with payment systems, providers and gateways, including 3DS.