Principal Engineer in London

About Us: At Masabi, we’re driving the fare payment revolution, powering the journeys of millions all over the world. We build fare collection platforms that allow riders to seamlessly buy and present tickets for public transport either on their mobile phones, from a ticket machine, or even by tapping their bank card to travel. Our Justride platform is used in over 250 locations globally, including some of the largest cities in the world. With our industry-first mobile ticketing SDK, we’ve partnered with large players in the transport space, including Uber, Moovit and Transit.

Your own journey is important to us too. Choosing a role here means joining a network of innovators from all walks of life; a group of passionate individuals who consistently deliver. Here, you’ll find the tools you need to build the career you want. Whether you’re taking the direct route or trying a new path, we’ll support you no matter what.

The Role: We’re looking for a Principal Engineer to join Masabi’s Architecture team. This is a senior role for someone who combines deep technical expertise with strong judgement and the ability to operate across teams. You’ll help shape the technical direction of Masabi’s platform while staying close enough to the detail to design, review and deliver meaningful technical work. Working across the engineering organisation, you’ll act as a senior technical leader: defining and evolving architecture, guiding complex decisions, and contributing hands-on where it matters most.

Responsibilities:

• Shape Masabi’s platform architecture, including platform blueprint definition, standards and best practices.
• Design and deliver scalable, robust, cost efficient services aligned with platform blueprint.
• Stay hands-on in code and technical delivery, including reviews and targeted contributions.
• Identify and work through complex platform challenges related to scalability, performance, resilience and cost.
• Act as a senior technical advisor across engineering teams, supporting and influencing technical decisions and ensuring Masabi standards are followed.
• Shape and contribute to technical roadmap planning and prioritisation of platform improvements.
• Support RFP estimation and technical scoping for complex initiatives.
• Produce clear, high-quality technical documentation and architecture artefacts.
• Improve how architecture is understood and applied across engineering and the wider business.
• Contribute to and help shape technical forums and working groups, including areas such as API and architecture governance.

About You: You bring strong experience designing and evolving distributed systems and microservices architectures. You’ve operated at Principal or Staff level, shaping technical direction across multiple teams or domains. You are comfortable staying hands-on, contributing in code, design and delivery when needed. You have strong experience with cloud platforms (AWS preferred) and modern infrastructure practices. You’ve worked on systems where scale, reliability, performance and cost trade-offs matter, and can navigate those decisions thoughtfully. You have proven experience in data architecture (e.g. data platforms, pipelines, warehousing or data lakes). You can take loosely defined (early stage) business or technical problems and turn them into clear, actionable technical approaches. You communicate complex ideas clearly and effectively, and produce structured documentation that helps both technical and non-technical audiences make decisions. You’ve contributed to engineering standards, architecture patterns or platform direction. Interest in or exposure to AI-enabled systems, particularly understanding architectural implications in production.

Nice To Have:

• Experience with REST API design in complex, multi-service environments.
• Experience breaking monolithic applications into microservices architectures.
• Experience with event-driven architectures (e.g. Kafka, schema governance).
• Experience improving cloud cost and system efficiency at scale.
• Familiarity with a range of tools and technologies including: Development: Kotlin, Java; Data storage: DynamoDB, MySQL; Infrastructure as code and CI/CD: Terraform, GitLab CI/CD.

Some of Our Benefits: 25 days of holiday per year plus the option to buy another 5 days pro-rated. Private Healthcare via AXA, including pre-existing conditions and mental health. Life Insurance. Menopause support. Choice of workstation. Ability to work for up to 3 months per year from any country in the world (certain limitations). Pension scheme. Training allowance of up to £1000 per year. £200 annual allowance for any home office need or improvement. Enhanced family leave pay. Cycle to work scheme. Regular social gatherings with a monthly allowance for each employee. Fun and collaborative environment with a focus on making a difference in the world.

Careers at Masabi are for people going places - driven by a mission to make transit fair and accessible for all. We are a network of innovators from all walks of life, passionate about making a difference. At Masabi, we operate with openness and trust, creating an environment where everyone feels empowered to bring their whole, authentic selves to work. Whoever you are, just be yourself. We welcome applications from underrepresented groups, including disabled and neurodivergent people, and can make adjustments at any stage of the process. You’re also welcome to share your pronouns whenever you feel comfortable. Together, we simplify journeys, remove barriers, and improve daily life for millions.

Why Join Masabi? Driven by Purpose – We believe in journeys made simple. The work isn’t always easy, but the best things never are. Encouraged to Accelerate – Masabi is going places and our people are in the driving seat. Whether you’re taking the direct route or exploring new paths, we support your journey. Advancing with Empathy – We put people first and foster a culture of learning, not blame. No matter your cargo, we share the load. We’re already powering journeys - are you ready to join us?