Principal Engineer

Masabi

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 - Payments to join Masabi’s Architecture team, with a primary focus on our payments domain. This is a senior role for someone who combines strong technical judgement with deep payments experience. You’ll shape the technical direction of our payments platform while staying close enough to the detail to design, review and support meaningful technical work. Working across the engineering organisation, you’ll act as a senior technical leader within the payments domain: contributing to architecture, guiding complex decisions and helping teams build scalable, resilient systems that support millions of journeys worldwide. The role suits someone who can move between system-level thinking and implementation, who understands trade-offs, can navigate ambiguity and helps turn complex or loosely defined problems into clear, practical technical approaches. LOCATION_ // This role is open to candidates based anywhere in the UK, with the flexibility to work fully remotely. For those based in or around London, we also offer the option of hybrid working from our London office. RESPONSIBILITIES_ * Shape the technical direction of Masabi’s payments platform, contributing to architecture, standards and engineering best practices * Design and deliver scalable, secure, resilient and cost-effective payment solutions aligned with Masabi’s platform direction * Support teams in building towards a modern, microservices-based architecture while balancing delivery priorities and long-term platform health * Stay close to technical delivery through architecture reviews, design discussions and targeted hands-on contribution where needed * Identify and work through complex technical challenges related to scalability, resilience, operational performance and system evolution * Act as a senior technical advisor across engineering teams, supporting and influencing technical decisions, particularly within the payments domain * Work with external providers and payment partners on integrations, technical alignment and problem-solving * Contribute to technical roadmap planning, prioritisation, technical scoping and architecture discussions for complex initiatives * Produce clear technical documentation and contribute to engineering standards, technical forums and good practices across the organisation ABOUT YOU_ * Strong experience working on payment systems, including integrations with PSPs, gateways or acquirers * Good understanding of payment flows, transaction lifecycles and system design considerations * 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 * Strong judgement and the ability to balance short-term delivery with long-term architectural outcomes * Comfortable navigating ambiguity and turning complex problems into clear, practical technical approaches * Clear and thoughtful communicator, able to engage both technical and non-technical audiences * Comfortable being hands-on where needed, while maintaining a focus on system-level impact * 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’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 transit payments (e.g. contactless EMV, tap-to-ride systems) * Familiarity with card schemes (e.g. Visa, Mastercard, Interac) * Experience working in complex, multi-service or event-driven architectures * 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?

9fin

About 9fin 9fin is the AI platform powering global debt markets — the world’s largest asset class at over $145 trillion. Debt markets are vast, global, and mission-critical, yet still run on fragmented data, PDFs, and manual workflows. 9fin replaces this broken infrastructure with a single platform that centralises proprietary credit data, deep analysis, and high-value workflows across global markets. Today, 9fin powers teams at 300+ blue-chip institutions worldwide, including global banks, asset managers, private equity firms, law firms, and advisors. The business is scaling at exceptional speed, with rapid expansion in the US and best-in-class retention driven by deep workflow adoption. We’re at a defining inflection point. With proven product-market fit and strong, global market pull, 9fin is accelerating toward becoming the category-defining platform for debt markets worldwide. WE'RE LOOKING FOR A PRINCIPAL ENGINEER TO OWN THE HARDEST TECHNICAL PROBLEMS AT 9FIN — THE ONES THAT CUT ACROSS TEAMS, DON'T BELONG CLEANLY TO ANY SINGLE DOMAIN, AND HAVE THE HIGHEST CONSEQUENCE IF THEY GO WRONG. 9fin sits at the intersection of financial data and AI. We ingest, model, and surface complex debt capital markets intelligence at scale. What we need now is someone who works across all of our areas (from AI, to Analytics, Platform, and Product Engineering) — setting the architectural standard, owning the foundational problems nobody else owns, and being the senior technical voice that makes the whole thing cohere. This is not a domain lead role. It's not advisory either. It's for someone who is energised by complexity and ambiguity, who wants to own the problems that are genuinely hard, and who can move between deep technical work and cross-org influence without losing credibility in either direction. WHAT YOU'LL OWN These are the cross-cutting problems that don't belong cleanly to any one team — but that everything else depends on. Core data model and entity resolution 9fin's value depends on how well we understand financial entities and the relationships between them — issuers, instruments, deals, counterparties, legal documents. This is hard: data is messy, sources conflict, and the model has to serve analytics, AI, and product simultaneously. You'll own the decisions that shape this foundation and hold the standard for how we model and resolve financial data at scale. Foundational architectural decisions When a decision is big enough to affect multiple teams and long-lived enough to be hard to undo, it lands with you. You'll write the RFCs, facilitate the debate, make the call, and be accountable for the outcome. WHAT YOU'LL OVERSEE You'll work closely with the Heads/Directors of Analytics, AI, Platform, and Product Engineering — not to run their domains, but to raise the bar across all of them. * Bring architectural coherence to decisions made within individual domains * Identify technical risks and compounding complexity before they become incidents * Set standards for engineering quality — system design, observability, reliability, API design — that every team builds to * Be the senior technical voice in cross-team planning, roadmap discussions, and major build vs. buy decisions * Mentor and stretch the most senior engineers across the org WHAT WE'RE LOOKING FOR You're the person who: * Has operated at principal or staff level in a data-intensive, fast-moving engineering org — and has the range to show for it * Can credibly walk into a conversation about data pipeline architecture, RAG evaluation, API design, or system scalability — and add something useful in all of them * Owns problems, not just opinions. You're not here to review and advise; you're here to make calls and be accountable for them * Writes code when it matters — the proof of concept that validates a direction, the deep dive that unblocks the team, the PR that sets the standard others build from * Has strong opinions about what good engineering looks like and can defend them without being precious about being wrong * Is energised by the problems nobody else can solve, not unsettled by them Technical bar: * Deep experience with complex data modelling, entity resolution, and data pipelines in production environments * Proven experience designing and shipping AI/LLM systems — RAG, structured extraction, evaluation frameworks — beyond the prototype stage * Strong backend and distributed systems knowledge: APIs, service architecture, scalability, observability * Experience making and owning foundational architectural decisions that affected how an entire engineering org worked * Proficiency in Python; comfort across the stack where it matters Nice to have: * Experience with financial data, legal documents, or other semi-structured, domain-rich datasets * Background as a founding engineer, early-stage CTO, or technical lead who has built systems from scratch and lived with the consequences WHY THIS ROLE * The problems you'll own are genuinely hard — messy financial data, complex entity relationships, AI systems where correctness really matters * You'll have real authority over foundational decisions, not just influence over them * 9fin's engineering org is strong and growing — you'll be working with and stretching great engineers, not compensating for weak ones * High ownership, high impact, and the chance to shape how a serious data and AI company scales its technical foundations Benefits We’re a scaling start up and we enjoy sharing our success, when the company succeeds, we always reinvest that in our people. We also offer huge amounts of responsibility, an abundance of opportunity for growth and a platform to truly excel. Financial & Insurance * Competitive Salary (our salary bands are benchmarked at the top end of the market) * Equity options * Pension (your minimum contributions are 4% with 9fin matching up to 7%) * Private Medical Insurance * Paid sick leave with Income Protection for long periods of illness * Group Life Assurance * Season Ticket Loan & Cycle to Work schemes Time off * 25 holiday days per year * Local public holidays (with the ability to exchange them for alternative days) * Hybrid working model, to allow you the flexibility to decide how, where and when you do your best work * Work abroad for up to 3 months a year * 1 month paid sabbatical after 5 years of service * Enhanced parental leave & flexible working arrangements available Training & Culture * Professional learning and development budget * Quarterly team socials * Summer and Winter company social events 9fin is an equal opportunities employer At 9fin we are dedicated to building and promoting a fair and inclusive workplace where everyone can reach their full potential and truly belong. We recognize that building diverse teams enables a more creative and productive environment. If you’re excited about this role but your experience doesn’t perfectly align with the job description, we encourage you to apply anyway. You might just be who we’re looking for — either for this role, or perhaps another.

CreateFuture

CreateFuture is fast becoming the UK’s most recognisable digital consultancy, with years of experience building digital products and services for major organisations whilst putting our people first. We have offices in the centre of Edinburgh, Leeds, Manchester and London as well as remote employees located throughout the country.  We are a team of creators - whether that’s code, project plans, go to market strategies, culture initiatives, marketing campaigns, large language models or people policies. And together, with our clients, we create the future. This has seen us collaborate and partner across a multitude of industries and sectors, with the likes of PayPal, Adidas, NatWest, FanDuel and Money Saving Expert to name just a few. Our reputation as a partner determined to deliver high-quality, robust and thoughtful products has enabled us to scale to over 500 people in the last couple of years, and it is our amazing people - along with the safe, supportive and friendly culture we have built - that makes CreateFuture a great place to work. Don’t just take our word for it though, we have been recognised by Best Workplaces UK multiple years in a row - across a number of categories - and our employee exit rate is astonishingly low. Join us on our journey… Let’s create something awesome, together, today. PRINCIPAL ENGINEER ABOUT THIS ROLE The bar has moved. Five years ago a strong engineer was measured by what they could build and how well they could mentor others to build it. Today, with Claude Code and agents, we produce quality work at a speed that would have looked superhuman in 2022. What separates exceptional from good is no longer typing speed or local craftsmanship. It is the complete package: architecture, deep engineering foundations, communication, system thinking, and the judgement to direct both your own intelligence and AI toward outcomes that matter.  Exceptional people at this level are not the best implementer in the room; they are the person whose specifications, decisions, and review judgement compound into systems that work in production and that others (and agents) can build on. They are a force multiplier, they hold a room at the highest levels, and clients treat them as the SME by default. YOUR MINDSET The mindset is the engine, and it is almost impossible to teach retrospectively. You are outcome obsessed, not output obsessed and you care whether the problem was actually solved - you resist the ego instinct to admire a clever solution and ask whether it was needed at all. You are intellectually honest about uncertainty, taking a trust-but-verify approach and assuming the surprising bug is the one that will burn. You are deeply pragmatic, which matters at CreateFuture where pace counts: you have outgrown the religious wars about platforms, languages and patterns, you hold opinions loosely, and you decide for the systems in front of you, not the ones you wish you had. You have a bias toward delivery: the smallest thing that works, then iterate, treating documents and meetings as means to that end.  And you are relentlessly curious beyond any immediate need, wanting to know how the database actually stores things or why a Claude Opus inference call costs what it does, which keeps you several layers ahead while the rest of the team is still reading the API docs. AI AS THE ACCELERANT For a Principal to be truly exceptional, this is now already a first-class competency in your arsenal, not a side skill.  An engineer who is brilliant by last year's standards but not fluent with AI is not exceptional in 2026. In practice that means: * Setting AI up to succeed. You treat context engineering as a craft (the right files, specs, examples and constraints), and you architect systems with clean interfaces, good naming, machine-readable specs and knowledge bases so the codebase is a quality baseline AI can work on later. No separate ivory-tower architect required. * Reviewing and choosing well. You read far more code than you write, and your value is in the quality of review: catching the silent assumption, the security flaw, the architectural drift, knowing where models fail and looking there first. You pick the right tool for the job (Claude Code for a deep refactor, an inline assistant when that is enough, a sub-agent for parallel work, the right model for analysis versus generation) and you know the constraints differ by client, an enterprise like PayPoint or Natwest versus a scale-up type business like Zuto or OAG. * Working with non-determinism. You see where AI moves the bottleneck and help people left and right of you unblock the value stream. You build with AI components but know success is no longer a binary, reaching for evals, golden datasets, structured outputs and fallback paths as naturally as you reach for unit tests. TECHNICAL BREADTH ACROSS THE FULL STACK Exceptional means depth in at least one area but competence everywhere the system reaches. * Backend: an instinct for distributed systems (what fails, what is eventually consistent, where queues back up), APIs that age well, thoughtful data modelling, and an understanding that languages are mostly syntax differences you can close with AI. * Cloud: cost-aware and security-aware by default, reaching for IaC, composing the primitives rather than stitching together managed services and hoping it works. * Data: modern pipelines, governance and lineage, increasingly vector stores and embeddings, with data quality treated as seriously as production code because garbage in, garbage out is far worse once AI features depend on it. * Web and mobile: past the framework arguments, with a clear view on what you would pick today, and able to build "good enough" front ends yourself with AI. Full-stack here means seeing the platform as one system and knowing which levers matter most. It does not mean front-end work with a few Node.js servers. SYSTEM THINKING, CONSULTING AND COMMERCIAL JUDGEMENT At CreateFuture we work in a consultancy context, where many otherwise excellent IC engineers can struggle.  You know technology is roughly 30% of the picture; the rest is design, argument and reasoning, commercial and political acumen, and the clarity to frame outcomes for a COO, CTO, CIO or CEO in their own language. You know when gold-plating is wasteful, you can name when a project's real problem is not technical and say so even when it is awkward, and you have a strong sense of what is durable versus what is fashion.  You are not the engineer who introduced the team to seven new technologies last year; you are the one who removed three and quietly made the remaining stack stronger. LEADERSHIP MENTALITY Technical work is necessary but no longer sufficient. By default you raise the level of everyone around you, regardless of discipline. * Communicate clearly and frequently (documents, decisions, post-mortems, design notes); the written artefact is the machine-readable context we can feed to AI later. * Make decisions and own them. You don't escalate everything or hoard control, and you are willing to be the benevolent dictator when it is your turn. * Mentor in AI fluency, not just code: tooling, prompting and review discipline, so your team is twice as productive a year from now. * Need little line management. You communicate upwards, raise by exception, self-resolve, and can be trusted with financial controls. * Disagree well. You tell people they are wrong with evidence and no ego, and you change your own mind when you are shown to be wrong. WHAT WE'RE NOT LOOKING FOR * The gifted engineer who sits in a silo. This is a team game. * The one who is fluent with AI but ships without the guardrails and quality gates enterprise clients expect. * The one with strong technical opinions who cannot justify them commercially and gets defensive when challenged. * The pure manager who wants to orchestrate teams rather than get involved. This is about setting a new standard, not coordinating it. * The engineer who will not immerse in a client environment. This role will mean on-site work and trusted relationships built in person. We are not going back to working away from the client and being bypassed.     WHAT WE’LL OFFER YOU: We trust people to do their best work. That means flexibility over rigid rules, impact over activity, and real investment in your growth both professionally and personally. You’ll be part of a supportive, and friendly culture, surrounded by smart, curious people who care deeply about what they do. We offer flexible working, including hybrid and remote options. Our office hubs are located in Edinburgh, Leeds, Manchester, London and Bulgaria, with occasional travel to client sites or CreateFuture offices when needed. We trust you to manage your time balancing collaboration with client time and focused work. What matters is the impact you have, not how busy you look. OUR HIRING PROCESS We try to keep our hiring process clear, fair and respectful of your time. We aim to get back to everyone who applies and we will be upfront about where you are in the process. It usually looks like this: * Call with our Talent Acquisition Team  * Role specific capability interview  Depending on the role, we might also ask you to do a short presentation, a practical or technical task or have a values focused conversation. We will explain what is involved before anything happens. INCLUSION AT CREATEFUTURE  We believe diverse teams build better workplaces and better products. We want CreateFuture to be a place where people feel able to be themselves and do their best work. If you need any adjustments or support during the application process, just. We will do what we can to help. We look forward to your application!