Cassandra Database Engineer - NoSQL

About the role

The Financial Crime Technology team is seeking a specialist Apache Cassandra engineer to design and operate high‑volume, real‑time data platforms that support fraud detection. This contract role will work on a real‑time payment capture and replay platform, ensuring the underlying NoSQL infrastructure is robust and scalable.

Key responsibilities

• Design, implement and maintain Apache Cassandra clusters, including keyspace design, replication strategies and partitioning models.
• Develop and optimise data models aligned to query patterns, avoiding hotspots and wide partitions.
• Perform performance tuning such as compaction strategies, consistency level configuration, read/write path optimisation and JVM/GC tuning.
• Manage cluster operations – node additions/decommissions, repairs, backups and disaster‑recovery procedures.
• Monitor cluster health using Prometheus, Grafana, OpsCenter or equivalent tools.
• Support CQL query development and advise application teams on best‑practice access patterns.
• Collaborate with infrastructure and security teams on hardening, encryption (at rest and in transit) and RBAC implementation.
• Produce technical documentation, runbooks and operational procedures.

Required profile

• Degree in Engineering, Computer Science, Business Administration or a related field.
• Proven production experience with Apache Cassandra and NoSQL database engineering.
• Strong expertise in keyspace and table design, data modelling, replication strategy and consistency tuning.
• Solid CQL knowledge and understanding of Cassandra internals (SSTables, memtables, commit log, compaction, gossip, tombstones).
• Hands‑on experience with cluster management tools (nodetool, OpsCenter) and monitoring solutions (Prometheus, Grafana).
• Experience with security hardening, encryption and RBAC.
• Ability to create clear documentation and runbooks.

Required skills

• Apache Cassandra
• CQL
• Prometheus
• Grafana
• OpsCenter
• nodetool
• JVM/GC tuning
• Encryption (at rest and in transit)
• RBAC

What we offer

• Highly competitive umbrella day rate
• Hybrid working model (3 days onsite in London)
• Contract until 31 March 2026 with possible extension