Product Engineer

Product Engineer Job title: Product Engineer Location: London; full in-office working as default Start date: ASAP Reports to: CTO Compensation: BASE : £80,000 - £120,000 EQUITY : £80,000 - £120,000 ___________________________________________________________________________ COSINE AT A GLANCE At Cosine, we’re building autonomous AI engineers that plan, write, and ship code inside real development workflows. Cosine is designed for on-premise and virtual private cloud (VPC) deployments, including fully air-gapped environments. We build our agent tooling entirely in-house and post-train open-source models to deliver reliable, enterprise-grade coding performance in security-critical settings. In 2024, Cosine achieved a 72% score on OpenAI’s SWE-Lancer benchmark, placing us among the strongest real-world software-engineering AI systems evaluated. YC-backed and well-funded, Cosine was founded by experienced operators focused on building dependable, production-grade AI. This role is based in our Hoxton office, five days a week, because close collaboration, fast feedback, and shared context matter for the problems we’re solving. ___________________________________________________________________________ THE ROLE A Product Engineer at Cosine works closely across research, engineering, product, and design to turn advanced AI capabilities into intuitive, reliable tools for developers. You will be responsible for building and evolving Cosine’s user-facing product surfaces, including IDE extensions or dedicated apps and web applications that expose the power of our models through well-designed workflows and interfaces. Your work sits at the intersection of product, platform, and research, translating emerging model capabilities into concrete experiences developers can use every day. We focus on rapid product iteration without compromising quality. This means building systems that are performant, observable, and robust, while remaining flexible enough to evolve alongside fast-moving research and user needs. You will help define how developers interact with Cosine, from first use through advanced, production-grade workflows. ___________________________________________________________________________ YOUR MISSION Deliver a scalable, high-quality Cosine product experience by building IDE and web application interfaces and integrations that expose the power of our models in intuitive, reliable ways. RESPONSIBILITIES - Build end-user products (editor extensions and web applications and platform capabilities) that integrate with the Cosine platform APIs - Enable developers to use advanced language models to augment their workflows and problem-solving capabilities - Collaborate closely research to explore and validate new product experiences and capabilities - Translate emerging model capabilities into concrete, user-facing features - Maintain a high bar for performance, reliability, and usability across platforms - Be opinionated about and bring your own ideas to the table, we’re building for engineers, as an engineer you have a say in what you want to use. ___________________________________________________________________________ SKILLS & EXPERIENCE Frontend & Application Development - Experience building reactive, highly interactive applications (React, Svelte, Vue) - Experience with cli application development or local software development is a plus Backend & Systems - Comfortable with backend development - Experience designing and consuming REST APIs Developer Experience - Experience working with developer tooling - Familiarity with CI/CD pipelines - Experience with containerization Programming Languages - Strong experience with TypeScript and modern frontend frameworks - Knowledge of Node.js, Python, and Go is a plus Tooling & Infrastructure - Git, Docker, Webpack, npm - Monitoring and alerting tools (e.g. Grafana, Datadog) - Feature flagging systems ____________________________________________ ... (truncated, view full listing at source)