Position Summary: We are looking for a talented Senior Python Engineer to join our team responsible for transaction monitoring and exploration. This is a fully remote role, and we welcome applications from anywhere in Europe. As part of our Nexus squad, you will play a critical role in streamlining clients’ operations and smoothing their investigations on the Crystal platform. More details: crystalintelligence.com Duties and responsibilities: Owning the transaction monitoring part of the Crystal platform; Improving stability and observability of the owned services; Maintaining code to high-quality standards; End-to-end feature design and implementation; Coding, debugging, testing and delivering features and improvements in a continuous manner; Providing code reviews, assistance and constructive feedback to other team members; Performance optimizations (including database queries optimizations); Refactoring code as necessary. Required: 8+ years of commercial experience developing Python backend services and APIs for the web; Solid software architecture skills; Strong knowledge of SQL/NoSQL databases and data architecture, including PostgreSQL; Knowledge of testing principles at different levels of the system; Experience in developing client-facing solutions; Experience with distributed systems; Product-oriented mindset; Proficiency in English. Would be a plus: Experience with scalability and performance optimizations of large distributed systems. Experience with systems operating on large data volumes; Experience with the Flask framework; Passion for cryptocurrencies and blockchain technologies. No previous knowledge of Blockchain technology required. Tech stack: Redis, RabbitMQ, PostgreSQL, ClickHouse; Kubernetes, AWS + Hetzner; Python 3.14, Flask, Granian; Datadog, Grafana. You’ll get: AI tool of your choice: Cursor or Claude Code.