Back End Developer

About the role:

We're hiring backend engineers at Oolka to build the core services and platform infrastructure that our proprietary AI agent ecosystem relies on for executing live financial transactions. The engineering challenge is unique: your systems must support autonomous agents operating over hours or days, managing complex retries, inspecting live state, and recovering gracefully when external banking integrations stall.

You will own both building clean fintech services for core applications and solving the advanced platform problems that emerge when an AI system becomes a primary consumer of your backend. You'll architect resilience against non-linear execution paths while ensuring strict transactional correctness under retries, races, and unpredictable call sequences.

• Build scalable core services in Java (Spring Boot) or Python (FastAPI/Django) powering live financial workflows, user state management, and money-moving actions at scale
• Architect resilient multi-step state machines for long-running autonomous agent workflows, enabling partial recovery and step-level fixes without data loss
• Abstract external unpredictability by wrapping third-party integrations (banks, lenders, credit bureaus) behind robust domain-driven API contracts
• Safety-first design under non-linear execution flows, ensuring strict state consistency when retries and concurrent access occur
• Design rich, intent-aware APIs with clear execution status indicators and machine-readable context specifically tailored for AI agents and frontend clients
• Create clean domain boundaries and reusable backend modules to scale solutions across diverse financial verticals

Required qualifications:

• 2–4 years of production experience building backend services in Java, Python, or a similar language with strong concurrency fundamentals
• Hands-on expertise with Spring Boot for RESTful web services OR FastAPI / Django for modern async-first architectures
• Proven working experience designing relational databases (PostgreSQL / MySQL), including complex schema design, performance indexing strategies, and defining precise transactional boundaries
• Strong ability to model clean domain boundaries using Domain-Driven Design principles and write clear API contracts that stand the test of time
• Demonstrated experience reasoning about multi-step workflows in distributed systems: message queues (Kafka/RabbitMQ), asynchronous execution patterns, retry logic strategies, and failure recovery mechanisms
• Clear written and verbal communication skills with the ability to translate evolving requirements into simple, durable architectural designs