At a Glance
- Tasks: Build innovative web applications and tools that leverage advanced AI capabilities.
- Company: Join Cosine, the UK's leading AI lab for autonomous software engineering.
- Benefits: Enjoy a competitive salary, equity options, 30 days holiday, and a dog-friendly office.
- Other info: Collaborative environment focused on work-life balance and professional growth.
- Why this job: Make a real impact in tech by shaping how AI is used in critical industries.
- Qualifications: 5+ years in software development with strong skills in frontend frameworks and APIs.
The predicted salary is between 70000 - 90000 £ per year.
Location: London; full in‑office working as default
Start date: ASAP
Reports to: Head of Engineering
Compensation: BASE : £70,000 - £90,000 EQUITY : £70,000 - £90,000
Cosine is the UK's frontier AI lab for autonomous software engineering. 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. Our offerings can be used as SaaS, deployed on VPC, on‑prem or fully air‑gapped. Through this flexibility, we are able to service large‑scale, highly regulated enterprises and industries including defence, financial services and healthcare.
The role A Full Stack Product Engineer at Cosine works closely across research, engineering, infrastructure, 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 dedicated apps and web applications that expose the power of our models through well‑designed workflows and interfaces.
Your Mission: Push the boundaries of what an autonomous agentic AI engineer can do by building scalable, high‑quality web application interfaces and integrations that expose the power of our models in intuitive, reliable ways.
Responsibilities:
- Build end‑user products (command line interfaces, 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 with 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
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: Experience 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, Kubernetes, GCP; Monitoring and alerting tools (e.g. Grafana, Datadog); Feature flagging systems
You Might Thrive in This Role If You:
- Have 5+ years of experience building production‑grade software.
- Have shipped and maintained complex frontend or full‑stack applications used by technical users.
- Are comfortable building highly interactive web or IDE‑based experiences using modern frameworks (e.g. React, TypeScript).
- Have experience designing and consuming APIs, and understand how frontend and backend systems evolve together.
- Enjoy working close to the product surface, translating ambiguous ideas and model capabilities into intuitive developer workflows.
- Care deeply about developer experience, performance, and reliability—not just functionality.
- Are comfortable iterating quickly, running experiments, and refining products based on real user feedback.
- Can operate effectively in a fast‑moving environment with evolving priorities and incomplete information.
Cosine is an equal opportunity employer. We value diverse backgrounds, perspectives, and ways of thinking, and we’re committed to creating an inclusive and respectful workplace. We encourage applications from anyone who meets the role requirements, even if you don’t meet every single qualification.
Compensation, Benefits & Ways of Working:
- Competitive salary, benchmarked to the market
- Equity / share options
- 30 days’ holiday + bank holidays
- Genuine 9–5 working hours
- Dog‑friendly office
- Weekly team breakfast & lunch
- Monthly socials
- Pension
- High‑quality equipment to do your best work
This role won’t suit everyone. But if you want structure, clarity, strong collaboration, and a team that takes both the work and work‑life balance seriously, it’s a great place to be.
Product Engineer employer: Cosine Group
Cosine is an exceptional employer, offering a collaborative and innovative work environment in the heart of London. With a strong focus on employee well-being, we provide competitive salaries, equity options, and generous holiday allowances, all while fostering a culture that values work-life balance and inclusivity. Our commitment to professional growth and development, combined with the opportunity to work on cutting-edge AI technology, makes Cosine a truly rewarding place for talented engineers looking to make a meaningful impact.
