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Tessl is a Series A AI startup building the context layer for AI coding agents and a platform for AI-native software development. Founded by Guy Podjarny and backed by Index Ventures, Accel, GV, and Boldstart, the company raised over $100M and was ranked #2 in Sifted EU's B2B SaaS Rising 100 and #20 in Sifted's AI 100.
As a Software Engineer, you'll join the engineering team to build real-time AI-native workflows, tooling, and interfaces that reshape how developers create and maintain software. You'll work with high autonomy in a fast-paced, collaborative environment balancing speed with thoughtful execution.
Key responsibilities include: designing and implementing new functionality in collaboration with product and design teams; rapidly prototyping language integrations for the code generation pipeline; building proof-of-concepts for innovative ideas; refining UI/CLI interactions with designers; integrating third-party services; planning scalable architectures supporting platform collaboration; establishing end-to-end testing strategies; and leading technical vision for new product capabilities.
You'll need 5+ years of proven software engineering experience with demonstrated expertise in code modularity, structure, and working across mature codebases and rapid prototyping environments. Essential qualifications include comfort in high-autonomy early-stage startup settings, proven daily usage of AI coding tools and agents, and excitement about experimenting with new AI approaches to transform software engineering.
Nice-to-have skills include AI product or developer tools background, rapid prototyping experience, polyglot programming across multiple paradigms (JavaScript/TypeScript, Python, C/C++, Haskell), collaboration with AI researchers, REST API and JSON:API experience, infrastructure work (CI pipelines, Kubernetes), and open-source project contributions.
The role is based in Tessl's 10,000 sq. ft. Kings Cross office in London's AI hub, with a requirement to be in-office at least 3 days per week (Monday, Tuesday, Thursday anchor days). Benefits include 25 days holiday, comprehensive health insurance (dental, vision, extended to partners/dependents), company-matched pension, commuting stipend for those outside London, and cycle-to-work scheme.
