Staff Engineer Full Stack

About ResultFlow.ai

At ResultFlow.ai, we build AI that helps ecommerce stores convert more of their visitors into customers. Merchants add our JavaScript plugin to their site, and our AI runs experiments and personalises their pages automatically, carrying learnings from one store to the next. It is a genuinely hard problem that spans frontend, backend, data, and LLM systems, all running on real, live stores where correctness matters.

We are a small, fast-moving team that makes decisions with data and ships quickly. We are looking for a Staff Software Engineer or Senior Staff Software Engineer to own significant parts of our product and help raise the bar for how we build.

This is a hands-on, individual-contributor role. You will be in the code every day. The initial days will be hectic and we leverage agentic coding to ship maximum code. Your role is not management, it is individual contribution. What sets it apart from a senior role is scope: you will own a whole area of our product rather than a set of individual tasks, take significant and often ambiguous problems from idea to shipped system, and pull other engineers along with you as you go.

You will work across the full stack: frontend that runs on third-party sites, backend APIs and integrations, data at scale, and LLM-powered systems. You will make the architectural calls within your area, and you will be someone the team relies on to turn a fuzzy problem into a working result.

• Own a system or area of the product end to end, including the messy, ambiguous parts that do not come with clear instructions.
• Make sound design and technical decisions within your domain, and explain and defend the trade-offs.
• Take vague business or product requirements, shape them into a clear technical plan, and execute.
• Care about how your systems behave in production: correctness, performance, and maintainability over time.
• Raise the level of the engineers around you through how you build, review, and think, without managing them.

• 6 to 11 years of professional software engineering experience.
• A track record of owning projects or systems that span multiple components, not just building individual features inside someone else's design.
• Deep, hands-on strength across most of the stack:
• Frontend: strong understanding of how the browser works (rendering, the DOM, the event loop, networking, performance).
• Backend: strong command of a language such as Python or Java, with solid experience in API design, authentication, and third-party integrations.
• Deployment: comfortable deploying and operating systems, on a VPS or via orchestration such as ECS or Kubernetes.
• Data: experience with data warehouses and data at scale.
• ML and LLMs: a solid grasp of core ML concepts and hands-on experience building with LLM APIs, including their parameters and failure modes.
• Ownership and judgment: you take responsibility for outcomes, make sound calls under ambiguity, and make the team better.
• The mindset we value across the whole team: data-driven, questioning, strong opinions held loosely, a fast and deep learner, a sense of urgency, and clear communication.

• Experience with experimentation systems, A/B testing or bandit methods, personalisation, or data instrumentation pipelines. This is the core of what we do.

Our hiring is work-first. If you progress, you will complete a practical task and then discuss it with us in depth, including your design and technical decisions, so we can see how you actually think and build. Using AI tools is welcome throughout, as long as you understand and can explain everything you produce.