About this role.
Masabi is seeking a Principal Engineer to join its Architecture team, driving the technical direction of the Justride fare payment platform used globally. This senior role combines deep technical expertise with strong judgment, requiring hands-on contributions in code, design, and architecture. The ideal candidate has experience shaping distributed systems and microservices, working with AWS, and tackling scalability and performance challenges. They will act as a technical advisor across teams, define platform blueprints, and produce clear documentation. The position offers an opportunity to influence a platform serving millions of users worldwide.
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Cover letter sample
I am excited to apply for the Principal Engineer role at Masabi. With over 10 years of experience designing and evolving distributed systems and microservices architectures, I have a strong track record of shaping technical direction across multiple teams. My hands-on expertise with AWS and modern infrastructure practices aligns perfectly with Masabi's platform needs.
I have successfully led architecture initiatives that improved scalability, reliability, and cost efficiency, and I am comfortable navigating ambiguity to turn complex problems into clear technical approaches. I am particularly drawn to Masabi's mission of driving the fare payment revolution and would welcome the opportunity to contribute to a platform used by millions globally.
I look forward to the possibility of discussing how my experience can support Masabi's technical vision.
Sample interview questions
At my previous company, we were migrating a monolithic service to microservices. We had to choose between using AWS Lambda for cost efficiency and EC2 for better performance. I led a proof-of-concept comparing both options under realistic load, factoring in cold start latency and throughput. We ultimately chose a hybrid approach: Lambda for bursty, low-latency endpoints and EC2 for high-throughput, steady-state services. This balanced cost and performance while meeting SLAs.
I allocate a portion of my time each week to direct code contributions, often tackling complex or cross-cutting issues that unblock teams. I also participate in design reviews and pair programming sessions. By staying close to the implementation, I ensure my architectural guidance is grounded in practical realities. Additionally, I mentor senior engineers to amplify my impact.
I would start by defining clear service boundaries, using an event-driven architecture with message queues for asynchronous processing. The system would be stateless where possible, using AWS services like DynamoDB for high-throughput data and SQS for decoupling. For resilience, I'd implement circuit breakers, retries with exponential backoff, and multi-AZ deployment. I'd also design for eventual consistency where appropriate, using idempotency keys for critical operations.
I believe in collaborative governance. I would establish an architecture forum with representatives from each team to discuss and propose standards. For each standard, we'd document the rationale, trade-offs, and examples. I'd also create a lightweight review process for new services or major changes to ensure alignment. To keep standards evolving, we'd hold regular retrospectives and update them based on lessons learned.
At a previous role, we had a data pipeline that was failing to meet latency requirements due to a bottleneck in the ETL process. The pipeline ingested real-time events and needed to update a data warehouse for analytics. I redesigned the pipeline to use Apache Kafka for streaming and implemented a lambda architecture with both batch and stream processing. This reduced latency from hours to seconds and improved data freshness for business decisions.
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.
The role suits someone who can move between system-level thinking and implementation, someone who understands trade-offs, can navigate ambiguity, and helps turn complex or loosely defined problems into clear, practical technical approaches.
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
// You don’t need to have experience in every area listed above. If you bring strong fundamentals, good judgement and a willingness to learn, we’d still love to hear from you.
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?
Annual salary information is not provided for this position. Explore salary ranges for similar roles in our Salary Directory ›
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