About the Role
Nexus Technologies Ltd is seeking a Senior Software Engineer to join our rapidly growing Platform Engineering team in London. This is a pivotal role within our core fintech platform, where you will design and own the architecture of high-throughput microservices that process over £2 billion in transactions annually.
Working in close collaboration with our Principal Engineers, Product Managers and the wider technology leadership, you will be responsible for setting technical direction, mentoring mid-level engineers, and driving the adoption of engineering best practices across a team of 12 engineers. You will be embedded in one of our cross-functional squads focused on our real-time payments engine.
Our technology stack centres on Python (FastAPI, Celery), PostgreSQL, Redis, Kafka, and AWS (EKS, Lambda, RDS). We practise continuous delivery and expect all engineers to contribute to a culture of high quality, observable, and reliable software. You will have genuine autonomy to propose and implement technical improvements, and your voice will directly shape the roadmap of the platform.
This role offers flexible hybrid working — the expectation is 2-3 days per week in our Moorgate office, with the remainder remote. We are open to candidates based anywhere within the UK who can meet this requirement.
If you are excited by large-scale distributed systems, care deeply about code quality, and thrive in a fast-moving environment where you can have real impact, we'd love to hear from you.
Key Responsibilities
- Design and implement scalable, fault-tolerant microservices using Python (FastAPI) deployed on AWS EKS via Kubernetes
- Lead technical design reviews, architectural decisions, and ensure engineering standards are consistently upheld
- Drive the migration of legacy monolithic components to event-driven microservices using Apache Kafka
- Collaborate with product and data teams to define and deliver features from inception to production, with a focus on reliability and observability
- Mentor and support 2-3 mid-level engineers through code reviews, pairing sessions, and structured feedback
- Maintain and improve CI/CD pipelines (GitHub Actions, ArgoCD) and infrastructure-as-code using Terraform
- Participate in on-call rotation (approximately 1 week in 6) to support the production platform and resolve incidents in a timely manner
- Contribute to hiring efforts, including reviewing CVs, conducting technical interviews and helping define the engineering hiring bar
Requirements
Essential
- 5+ years of professional software engineering experience with Python or equivalent backend language
- Strong understanding of distributed systems, microservices design patterns, and asynchronous processing
- Hands-on experience with Kubernetes and container orchestration in a production environment
- Solid working knowledge of AWS services (EKS, Lambda, RDS Aurora, SQS/SNS)
- Experience building and maintaining CI/CD pipelines and IaC tooling (Terraform, Helm)
- Proven ability to lead technical initiatives and mentor less experienced engineers
Nice to Have
- Prior experience in a regulated industry (fintech, banking, insurance)
- Familiarity with Apache Kafka or event streaming platforms
- Contributions to open-source projects or a strong GitHub profile
- AWS Professional or Kubernetes CKA certification
Benefits
About Nexus Technologies Ltd
Nexus Technologies Ltd
Founded in 2014, Nexus Technologies is a Series C fintech headquartered in the City of London, providing real-time payment infrastructure and embedded finance APIs to over 350 enterprise clients across Europe. With a team of 280 employees spanning London, Dublin, and Warsaw, we process billions in transactions each year and are on a mission to make financial infrastructure as simple as sending an email.
We were named one of Deloitte's UK Technology Fast 50 in 2024 and 2025, and we are proud of our engineering culture that genuinely values autonomy, learning, and psychological safety.