Sr Principal, Software Engineer

FIS; Greater London; Hybrid; GBP 120,000 - 180,000; Full time

Job summary

FIS in London, within a newly acquired startup building an AI-enabled, autonomous banking platform for Tier-1 institutions, seeks a senior engineer to own core banking services from design to production. You will design APIs, ensure correctness, scale distributed systems, and lead incident response with observability and reliable deployments.

This role offers startup autonomy within a global enterprise. Strong Go or equivalent language experience, event-driven architectures, and a practical bias

Qualifications

• Deep experience designing and building complex distributed systems at scale.
• Strong understanding of concurrency, invariants, and failure modes.
• Experience with event-driven architectures and modern production practices.

Responsibilities

• Build and evolve banking capabilities from products to transactions and compliance.
• Define APIs, events, and data contracts for a coherent platform.
• Own services through design, testing, deployment, and operation.
• Contribute to observability, incident response, and reliability improvements.
• Promote engineering best practices and knowledge sharing.

Skills

Distributed systems

Go

Event-driven architecture

Kafka

Concurrency & consistency

Incident response

Observability

CI/CD

Tools

Kafka

GitOps

CI/CD tooling

Job description

Sits within a newly acquired startup building an AI-enabled, autonomous banking platform for Tier-1 financial institutions within the banking group.

The role builds, operates, and scales the services at the heart of the platform — spanning Core Banking, workflows, and compliance. These systems define financial products, manage accounts, execute and record money movement, orchestrate banking processes, and enforce regulatory rules at Tier-1 scale.

Requires deep experience with complex distributed systems, a correctness-first mindset, sound engineering judgement, and full end-to-end ownership from design through production operation.

KEY RESPONSIBILITIES

• Build and evolve the capabilities that bring modern banking products to life — from products and accounts through transactions, transfers, journals, balances, and interest, to durable workflows and compliance controls.


• Define reliable APIs, events, and data contracts that connect these capabilities into a coherent, auditable banking platform.

Production Ownership

• Own services throughout their lifecycle: design, implementation, testing, deployment, operation, and continuous improvement.


• Participate in on-call and incident response, diagnosing failures across distributed services, data infrastructure, and event-driven workflows.


• Establish effective observability, alerting, operational controls, and recovery procedures; learn from production incidents to improve reliability, performance, and operational maturity.

Architecture and Delivery

• Design systems for correctness, auditability, scalability, and resilience at Tier-1 banking scale, making pragmatic trade-offs between delivery speed, operational complexity, and long-term maintainability.


• Improve engineering practices across automated testing, CI/CD, safe deployment, rollback, and recovery.


• Use AI-assisted engineering, MCP servers, agent workflows, and automated runbooks where they materially improve engineering or operational outcomes.


• Contribute to team excellence through knowledge sharing, mentoring, and coaching, helping to develop technical capability and promote engineering best practices across the organization

REQUIRED EXPERIENCE & CAPABILITIES

• Deep experience designing and building complex distributed systems at scale, using a strongly typed, compiled language. Go is preferred, but deep experience with a comparable language is welcome.


• Experience with event-driven architectures and technologies such as Kafka or equivalent streaming platforms.


• Strong understanding of concurrency, consistency, invariants, idempotency, failure modes, and distributed-system trade-offs.

Production Experience

• Substantial experience operating and debugging critical systems in production, ideally including on-call and incident response across application, data, and infrastructure boundaries.


• Practical experience with observability, reliability engineering, capacity planning, deployment safety, and disaster recovery.


• Experience with automated testing, CI/CD, GitOps, and modern production-engineering practices.

Judgement and Communication

• Practical judgement and common sense, with the ability to evaluate and clearly articulate architectural trade-offs rather than apply technologies or patterns mechanically.


• Ability to explain complex systems in simple, precise terms and work effectively across coding, architecture, operations, and cross-team delivery.


• Effective use of AI to amplify genuine engineering expertise, with human ownership of design, validation, security, and production outcomes.

IMPACT & SCOPE

• Direct impact on core banking capabilities shipped to and supported in production for Tier-1 global institutions.


• High autonomy and accountability within a small, senior team.


• Ownership of mission-critical systems operating at enterprise scale.

WHY THIS ROLE

This role offers the autonomy, ownership, and technical depth of a startup, combined with the scale, stability, and long-term impact of FIS. Engineers in this role shape foundational banking infrastructure while operating with clear accountability, enterprise resources, and real-world production responsibility.