UX Engineer, HCI in London

CompanyA1 is building a proactive AI smart assistant for everyday users to bring intelligence to conversations, errands, organising and workflows. Our product focuses on achieving high reliability for long-running workflows, persistent context, and real-world task completion. The system must handle multi-step reasoning, interact with external tools, and remain reliable despite non-deterministic model behavior.

You will sit at the intersection of design and engineering, building the AI interfaces that users actually interact with. This is not a UI maintenance role. You will prototype, test, and ship new interaction patterns for AI-driven experiences where established conventions do not yet exist. This role is focused on HCI - building interfaces that make AI behaviour understandable, controllable, and useful in real workflows.

What You'll Be Doing

• Build and prototype AI-native product interfaces across web and mobile.
• Create functional prototypes of new HCI interaction models, including streaming responses, multi-step task flows, real-time feedback loops, and system state visibility.
• Translate design concepts into working code with high attention to usability, responsiveness, and motion.
• Experiment with UI patterns that show progress, uncertainty, confidence, failure, and recovery clearly to users.
• Build interfaces that let users supervise, correct, and redirect AI behaviour without micromanaging the system.
• Work closely with product, design, and ML teams to validate interaction ideas quickly.
• Contribute to frontend architecture and reusable UI components for AI product surfaces.
• Identify and fix usability, performance, and state management issues in AI-driven interfaces.

What You Will Need

• Strong frontend engineering skills in React, TypeScript, or equivalent.
• Experience building interaction-heavy or experimental interfaces.
• Strong product and UX instincts - you can tell when something is unclear or broken from a user's perspective.
• Ability to prototype rapidly in ambiguous environments with incomplete specs.
• Understanding of animation, responsiveness, frontend architecture, and UI performance.
• Interest in HCI interfaces and how to design for trust, control, transparency, and recovery.
• Comfort working at the boundary of design and engineering without clear handoffs.
• Ability to move fast while keeping the user experience clear and usable.

How We Work

The best products today in the world were built by small, world class teams. We are a high talent density and hands-on team. We make decisions collectively, move at rapid speed, striking a balance between shipping high quality work and learning. Joining our team requires the ability to bring structure, exercise judgment, and execute independently. Our goal is to put in the hands of our users a truly magical product.

Interview process

For design roles, we expect candidates to submit a portfolio as part of the application process. If there appears to be a fit, we'll reach out to schedule 2 rounds of interviews and a design assessment. Applications are evaluated by our team members. Interviews will be conducted via virtual meetings and/or onsite. We value transparency and efficiency, so expect a prompt decision. If you've demonstrated the exceptional skills and mindset we're looking for, we'll extend an offer to join us. This isn't just a job offer; it's an invitation to be part of a team that's bringing AI to have practical benefits to billions globally.