Member of Design Staff - Product Designer in London

Tessl is a fast-growing Series A startup based in London, founded by Guy Podjarny. We have raised over $100M from world-class investors including Index Ventures, Accel, GV, and Boldstart. This year we were ranked #2 in Sifted EU's B2B SaaS Rising 100 and #20 in Sifted's AI 100. At Tessl, we believe AI is transforming software development. AI Native Developers will define features, architecture, and workflows in specs, not code, guiding the work of AI agents. We are building the pioneering platform for this new paradigm and leading the developer movement and ecosystem around it. Joining Tessl means becoming an early team member with the opportunity to shape the future of how software is created and maintained.

About the role: Tessl is building the foundational infrastructure for how developers work with AI agents: the systems, standards, and tooling that make agent-assisted software development reliable, repeatable, and trustworthy at scale. We are a small team working on a genuinely new class of problem, and design is central to how we solve it.

We are looking for a Member of Design Staff who brings real craft and genuine curiosity. You will work closely with product managers, engineers, and researchers to shape how developers interact with technically complex systems and workflows. This is not execution work within a settled product. The patterns are still forming, and the person we hire will have a direct hand in shaping them. We also expect this person to be building a genuinely AI-native design practice: using the best available tools to move faster, think more clearly, and raise the quality of our work. We are not looking for someone who uses AI occasionally. We want someone who is actively developing how they work with it.

What you will work on:

• Design clear, usable interfaces across core product surfaces and developer workflows, balancing simplicity with the depth and configurability that expert users need.
• Translate nuanced system concepts into experiences that feel considered rather than overwhelming, grounding design decisions in real user behaviour and research.
• Run user research with developers and engineers, turning genuine observations into well-reasoned, specific design decisions.
• Collaborate daily with product managers and engineers throughout the full cycle of work: contributing early, iterating often, and treating designs as living documents rather than fixed deliverables.
• Contribute to a growing design system, bringing visual rigour and coherence to shared foundations that will hold up as the product and team scale.
• Develop an AI-native design process: use current tools across research, prototyping, and visual production, share what you learn with the team, and raise the bar for how design work gets done.

What we are looking for:

• Experience: 3 to 5 years of experience in product design, or equivalent, with a portfolio showing end-to-end ownership of real, shipped work. Strong visual design sensibility evident throughout.
• Technical fluency: A track record of designing for technically sophisticated users. You do not need to be an engineer, but you should be genuinely curious about how the systems you design for actually work.
• Tools and working practice: Strong proficiency in Figma, including component architecture and design system contribution. Comfort using AI tools as a serious part of your workflow, from research through to production. Familiarity with tools such as Dovetail is a plus.
• Collaboration: You work well in a fast-moving environment where priorities can shift and process is still forming. You are confident enough to take the lead on design direction and bring a clear point of view, but equally comfortable running with an idea that comes from elsewhere in the team.
• Domain experience: Prior experience in developer tools, productivity software, or AI/ML applications. You understand what it means to design for expert users.

We do not have all the answers yet. This is a role where you will help define new patterns, work at the edge of what is known, and shape how design is practised at a company that is still figuring things out in the best possible way. If that kind of challenge excites you, and you feel you would be a strong fit even if you do not meet every criterion listed, we would encourage you to apply.

Application Process: Here's an outline of what you can expect during our interview process:

• Introductory call
• Portfolio Review with Designer(s)
• Case study / White boarding
• Meet with Head of Product
• Leadership discussion

We care deeply about the warm, inclusive environment we're building at Tessl and we value diversity – we welcome applications from those typically underrepresented in tech. If you like the sound of this role but are not totally sure whether you're the right person, do apply anyway!