Jobs → Engineering → Senior Software Developer

About the Role We are looking for a Senior Software Developer to join Arkkosoft and focus on payment systems development using Elixir on AWS Cloud. Key Responsibilities • Develop payment features for donor payments, transactions, account provisioning, and reporting • Build and maintain backend services using Elixir on AWS Cloud • Integrate payment processors, prepaid card networks, and enterprise systems via REST APIs • Implement ACH transfers, real-time notifications, exception handling, idempotency, exactly-once processing, and reconciliation • Write secure, documented, tested code; participate in code reviews and performance improvements • Apply input validation, encryption, tokenization, and secure credential management • Use AI coding tools such as Copilot, Cursor, or Claude Code under PCI guidelines and AI code quality controls • Implement structured logs, traces, and metrics for production monitoring • Develop unit, integration, regression, and contract tests; resolve production defects • Support UAT, deployments, and on-call rotations • Participate in Agile ceremonies, documentation, knowledge-sharing, and platform modernization Requirements • 5+ years of backend or full-stack development experience • Strong experience with Elixir and backend development • Hands-on payment systems experience, including ACH, prepaid card APIs, or payment gateways • Knowledge of idempotency, exactly-once semantics, and payment reconciliation • Hands-on software engineering experience within the last 3 years • Experience with REST/GraphQL APIs, integration patterns, and API security • Knowledge of relational and non-relational databases, data modeling, query optimization, and transaction management • Experience with AWS Cloud, CI/CD, feature flags, and progressive delivery • Understanding of secure development, data protection, and regulated environments • Familiarity with AI coding tools, acceptable-use standards, and quality controls • Experience in regulated or consumer-scale environments where reliability matters • Agile/Scrum experience with Jira and Confluence