Senior/Staff/Principal AI Software Engineer

Senior / Tech Lead / Staff / Principal Software Engineers, AI Email App Levels: Senior / Tech Lead / Staff / Principal Location: Remote first company ** These roles will be a 0-1 building a global AI product as part of the Founding team and will consist of a generous Salary, Bonus and Equity package** About the Company Over 5 billion people use basic applications today, email, notes, tasks and calendar, and none of them are truly AI native. Our client's mission is to build proactive applications for anyone in the world, including people who are not used to complex prompting. They have just raised $100 million, backed by a globally recognised organisation and are bringing intelligence to conversations, errands, organising and workflows, with minimal to no prompting required. The first product reimagines email, moving users from writing and reading email to reviewing and approving AI completed work, with the ambition of cutting the average person's daily email time from around 4 hours to around 30 minutes. About the Role Our client is hiring Software Engineers for their AI Email App at Senior, Tech Lead, Staff and Principal levels, with seniority and scope matched to experience. You will help build the engineering layer that turns AI capability into a reliable, real world product, shaping architecture across backend services, APIs and client applications (mobile and desktop). At Staff and Principal level, this extends to leading a small team of senior engineers and owning critical architectural decisions as the system scales. This is a hands on role at every level. You stay close to the code, contribute to key technical decisions, and help ensure the system remains fast, reliable and coherent as it grows. Tech stack includes: Frontend: TypeScript, React.js/Next.js, HTML/CSS, Node.js, WebSockets/streaming APIs, REST/GraphQLDesktop: JavaScript/TypeScript/Node.js, Electron, SQLite and IndexedDB for local storage, WebSockets/IPCMobile (Android): Kotlin/Java, Coroutines and Flow, REST or gRPC, TensorFlow Lite for on device inference, MLKitBackend / AI systems: Python and Node.js, PyTorch/JAX, LLM APIs (OpenAI style, Anthropic, LLaMA, Qwen, other open source models), vLLM for inference serving, vector databases, SQL/NoSQL, Docker and Kubernetes What You Will Own Application engineering, spanning strategy and hands on execution across backend, mobile and desktopDesign of reliable systems for AI powered workflows, including state, orchestration, tool use, retries, fallbacks and failure handlingThe APIs and abstractions that connect AI systems to real world product experiencesAt Staff and Principal level: leading a small, senior engineering team and raising the technical bar through design reviews, code reviews and hands on mentorshipTrade offs across latency, reliability, cost, security and user experience, with the scale of impact increasing by levelStrong production foundations: observability, monitoring, testing and operational excellenceClose partnership with ML leadership to turn model capabilities into robust, shippable product experiencesMoving quickly while keeping the architecture simple, maintainable and ready to scale What Our Client Is Looking For Experience in application or product engineering for complex systems, at a level consistent with Senior, Tech Lead, Staff or Principal seniorityA strong, hands on background building and shipping backend systems used in production, ideally in Python or Node.jsExperience building AI powered products or systems that integrate with modern ML or LLM capabilities, such as Anthropic or OpenAI style APIsComfort working across backend and client platforms, such as React, TypeScript, Electron or Kotlin, with deep expertise in at least oneWorking knowledge of SQL and NoSQL data stores, and ideally vector databases for retrieval or persistent contextFamiliarity with Docker and Kubernetes, and how modern AI powered services are deployed and operated in productionStrong technical judgement and the ability to make decisions with incomplete informationA strong bias toward ownership, shipping and learning from real world usageHigh standards for code quality, reliability and engineering fundamentalsFor Tech Lead, Staff and Principal candidates: a track record of technical leadership, mentorship and raising the bar within an engineering team Outcomes You Will Drive Production systems that are observable, monitored and stable under real world loadDecisions that consistently balance speed, cost, reliability and user experienceFeatures across backend, mobile and desktop that work smoothly and reliablyMeasurable improvement in latency and reliability over time To be considered, please apply now with your latest CV .