Principal Architect

KAST; Greater London; Hybrid; GBP 140,000 - 190,000; Full time

Job summary

KAST is seeking a seasoned Principal Architect to own and drive our technical strategy as we scale a global fintech platform. You will be the primary authority for system design, ensuring high‑throughput transaction engines and a complex microservices ecosystem remain resilient, performant, and secure under heavy load.

You’ll partner with Engineering, Product and Security to set standards for building and deploying transactional infrastructure on AWS.

Qualifications

• 10+ years of software engineering experience with fintech platforms.
• Led large-scale payment or ledger systems or high-volume financial infrastructure.
• Expertise in microservices and event-driven design for scalable systems.
• Extensive AWS/cloud-native architecture experience.
• Knowledge of security and compliance standards in regulated environments.

Responsibilities

• Own the architectural vision for high-throughput platforms.
• Design for scale, reliability, and fault tolerance on AWS.
• Optimize transactional flows with sub-millisecond performance.
• Define coding standards and deployment patterns for autonomous teams.
• Lead AWS strategy to improve latency and cost efficiency.
• Mentor engineers and guide major technical decisions.

Skills

Fintech leadership

Distributed systems

Cloud - AWS

Security & compliance

Architectural leadership

Job description

Description

We’re looking for a seasoned Principal Architect / Architecture Lead to own and drive KAST’s technical strategy as we scale our global fintech platform. You will be the primary technical authority for our system design, responsible for ensuring that our high-throughput transaction engines and complex microservices ecosystem remain resilient, performant, and secure under massive load.

Department: Engineering

Location: London

You will partner with Engineering, Product, and Security leadership to bridge the gap between business growth and technical execution, setting the standards for how we build, deploy, and evolve our transactional infrastructure on AWS.

Location: flexible across Europe/APAC.

What You’ll Be Doing

• Own the Architectural Vision: Define and drive the long‑term technical architecture for KAST, ensuring our platform evolves to meet the demands of high‑throughput transactional volume.
• Design for Scale & Reliability: Lead the design and review of our distributed systems, ensuring our microservices architecture is built for fault tolerance, high availability, and massive scalability on AWS.
• Optimize Transactional Flows: architect critical path systems, including our payment processing, ledger management, and financial data consistency models, ensuring sub‑millisecond performance and auditability.
• Establish Engineering Standards: Define architecture principles, coding standards, and deployment patterns (CI/CD, IaC) that enable autonomous microservices teams to ship code safely and rapidly.
• Cloud‑Native Strategy: Lead our AWS strategy, optimizing resource utilization, latency, and cost while leveraging managed services to improve developer velocity.
• Drive Security & Compliance: Integrate security‑by‑design principles into our architecture, ensuring that our transaction‑heavy environment meets strict financial compliance standards (PCI‑DSS, SOC2).
• Influence & Mentor: Act as a force multiplier for the engineering organization by mentoring senior engineers, leading architecture review boards, and guiding major technical decisions.

What You’ll Bring

• Proven Fintech Leadership: 10+ years of software engineering experience, with a significant track record architecting large‑scale payment platforms, ledger systems, or high‑volume financial infrastructure.
• Distributed Systems Expert: Deep expertise in microservices architecture, event‑driven design, and the trade‑offs inherent in building consistent, high‑throughput distributed systems.
• Cloud‑Native Proficiency: Extensive experience designing and operating complex, high‑traffic applications on AWS.
• Data & Transaction Integrity: Strong understanding of database patterns for financial data, including transaction atomicity, consistency models, and handling distributed data across microservices.
• Strategic Influencer: Demonstrated ability to influence technical direction across multiple teams, manage stakeholder expectations, and drive consensus on complex architectural trade‑offs.
• Security & Compliance Awareness: Knowledge of designing for security within a regulated industry, understanding how to protect sensitive financial data while maintaining system throughput.
• Growth Mindset: Ability to balance immediate delivery needs with long‑term architectural debt management.