Senior Back-end Engineer

Company Overview & Vision

Founded in Singapore in April 2026, CITA Lab is a dynamic software development startup dedicated to building high-quality, custom blockchain-related products tailored specifically to our customers' requirements. Our diverse product lineup includes centralized/decentralized cryptocurrency exchange solutions, secure crypto wallets, smart contracts, dApps, and more. We turn complex blockchain capabilities into seamless, secure, and intuitive user experiences for clients worldwide.

Responsibilities

- Design, develop, and maintain scalable, high-performance backend services and APIs.
- Build reliable systems for transaction processing, payments, settlements, wallets, and other financial workflows.
- Design and maintain REST, RPC, GraphQL, and/or WebSocket APIs.
- Develop distributed and event-driven systems capable of handling high transaction volumes.
- Design service boundaries, data models, API contracts, and communication patterns.
- Improve system performance, latency, throughput, reliability, and scalability.
- Design robust retry, timeout, idempotency, reconciliation, and failure-recovery mechanisms.
- Build integrations with blockchain networks, payment providers, financial institutions, and third-party services.
- Design and optimize relational and NoSQL database solutions.

- Implement caching, message queues, and asynchronous processing where appropriate.

- Troubleshoot complex production issues across applications, databases, networks, and infrastructure.
- Participate in architecture reviews and technical design discussions.
- Conduct code reviews and establish backend engineering standards.
- Write comprehensive unit, integration, and end-to-end tests.

- Collaborate with Frontend, DevOps, Security, QA, and Product teams.
- Mentor other engineers and contribute to engineering best practices.

What you'll do

We are looking for an experienced Senior Backend Engineer to design, build, and operate scalable, secure, and highly available backend systems. You will work on core services supporting financial and blockchain products, including APIs, transaction processing, payment and settlement workflows, wallet integrations, real-time systems, and internal infrastructure. The ideal candidate has strong experience with distributed systems, microservices, databases, and high-concurrency backend applications. Experience in FinTech, payments, cryptocurrency, trading, or Web3 is highly desirable.

Requirements

• 5+ years of professional backend software engineering experience.
• Strong proficiency in at least one backend language such as Go, Java, Rust, Python, or Node.js/TypeScript.
• Strong understanding of data structures, algorithms, concurrency, and software design principles.
• Experience designing and operating production-grade distributed systems and microservices.
• Strong experience designing RESTful APIs and service-to-service APIs.
• Experience with relational databases such as PostgreSQL or MySQL.
• Strong understanding of database transactions, indexing, query optimization, locking, and concurrency.
• Experience with caching systems such as Redis.
• Experience with message brokers or streaming platforms such as Kafka, RabbitMQ, NATS, or equivalent technologies.
• Experience with asynchronous processing and event-driven architecture.
• Understanding of Docker, Kubernetes, and cloud environments such as AWS, GCP, or Azure.
• Experience with CI/CD and automated testing.
• Strong debugging and production troubleshooting skills.
• Experience with monitoring, logging, metrics, and distributed tracing.

Nice-to-have

• Microservices and service boundaries
• Distributed systems
• Event-driven architecture
• High-concurrency systems
• API design and versioning
• Database architecture
• Caching strategies
• Message queues and event streaming
• Idempotency
• Distributed transactions
• Eventual consistency
• Retry and timeout strategies
• Rate limiting
• Circuit breakers
• Horizontal scaling
• Fault tolerance
• Disaster recovery
• Observability
• Zero-downtime deployments