UX Engineer, HCI

📍 Job Overview

Job Title: UX Engineer, HCI

Company: Bjak

Location: London, England, United Kingdom

Job Type: Full-Time

Category: Engineering / Design (HCI Focus)

Date Posted: May 21, 2026

Experience Level: Mid-Level (2-5 years)

Remote Status: Hybrid (Remote within UK, potential for onsite in London)

🚀 Role Summary

• This role sits at the critical intersection of Human-Computer Interaction (HCI) and frontend engineering, focused on building novel interfaces for AI-driven products.

• You will be responsible for prototyping, testing, and shipping new interaction patterns for AI experiences where established conventions are still emerging.

• The core objective is to make AI behavior understandable, controllable, and genuinely useful within user workflows, emphasizing trust, transparency, and recovery.

• This position requires a blend of strong technical frontend skills and deep UX instincts to translate complex AI capabilities into intuitive and effective user interfaces.

📝 Enhancement Note: The job title "UX Engineer, HCI" strongly suggests a hybrid role that blends user experience design principles with hands-on software development. The emphasis on "AI-native product interfaces," "new interaction patterns," and "HCI" points towards a need for individuals who can both conceptualize and implement cutting-edge user experiences for artificial intelligence.

📈 Primary Responsibilities

• Build and prototype AI-native product interfaces across web and mobile platforms, focusing on innovative interaction models.

• Develop functional prototypes for new HCI interaction paradigms, including streaming responses, multi-step task flows, real-time feedback mechanisms, and clear system state visibility.

• Translate design concepts into high-quality, working code with meticulous attention to usability, responsiveness, and engaging motion.

• Experiment with and implement UI patterns that effectively communicate AI progress, uncertainty, confidence, failure modes, and recovery processes to users.

• Design and build interfaces that empower users to supervise, correct, and redirect AI behavior without requiring them to micro-manage the underlying system.

• Collaborate closely with Product, Design, and Machine Learning (ML) teams to rapidly validate interaction ideas and user experience hypotheses.

• Contribute to the frontend architecture, including the development of reusable UI components specifically tailored for AI product surfaces.

• Proactively identify and resolve usability, performance bottlenecks, and state management issues within AI-driven interfaces.

📝 Enhancement Note: The responsibilities emphasize rapid prototyping and experimentation, aligning with the early-stage nature of AI product development. The focus on "AI-native" interfaces and specific interaction models like "streaming responses" and "system state visibility" indicates a need for engineers who can think beyond traditional UI paradigms.

🎓 Skills & Qualifications

Education: While not explicitly stated, a Bachelor's degree in Computer Science, Human-Computer Interaction, Design, or a related field is typically expected for roles of this nature. Equivalent practical experience will also be strongly considered.

Experience: Mid-level experience (approximately 2-5 years) in frontend engineering with a demonstrated focus on building interaction-heavy or experimental interfaces.

Required Skills:

• Strong proficiency in frontend engineering, specifically with React and TypeScript, or equivalent modern JavaScript frameworks and languages.

• Proven experience in building interaction-heavy, experimental, or novel user interfaces.

• Excellent product and UX instincts, with the ability to critically assess and identify usability issues from a user's perspective.

• Demonstrated ability to prototype rapidly and effectively in ambiguous environments with evolving or incomplete specifications.

• Solid understanding of animation principles, responsiveness, frontend architecture best practices, and UI performance optimization.

• Keen interest in Human-Computer Interaction (HCI) principles and a passion for designing for trust, control, transparency, and error recovery in user interfaces.

• Comfort working collaboratively at the intersection of design and engineering, often without strict handoff protocols.

Preferred Skills:

• Experience with animation libraries (e.g., Framer Motion, GSAP) for creating dynamic and responsive UI elements.

• Familiarity with state management libraries (e.g., Redux, Zustand, Jotai) in complex applications.

• Experience with mobile development frameworks (e.g., React Native) or cross-platform UI development.

• Understanding of AI/ML concepts and how they translate into user-facing features.

• Familiarity with A/B testing and user research methodologies to validate interface designs.

📝 Enhancement Note: The requirements highlight a unique blend of technical depth in modern frontend stacks and a strong conceptual understanding of user experience and HCI. The emphasis on rapid prototyping and ambiguity tolerance suggests a startup-like environment where agility and self-direction are paramount.

📊 Process & Systems Portfolio Requirements

Portfolio Essentials:

• A curated portfolio showcasing a range of projects demonstrating your ability to build modern, interactive, and user-centric interfaces.

• Specific examples of projects where you’ve focused on novel interaction design, rapid prototyping, or experimental UI patterns.

• Case studies detailing your process for translating design concepts into functional code, highlighting problem-solving, and iterating based on feedback.

• Evidence of contributions to frontend architecture, reusable component development, or UI performance improvements.

Process Documentation:

• Detailed case studies that walk through your design and development process for key projects, including initial ideation, prototyping, implementation, and iteration.

• Documentation of how you approach problem-solving for complex UI challenges, especially those involving state management, performance, or intricate user flows.

• Examples of how you've collaborated with designers and product managers, illustrating your ability to bridge the gap between concept and execution.

• Clear articulation of how you measure the success and usability of your interface designs.

📝 Enhancement Note: Given the role's focus on "new interaction patterns" and "experimental interfaces," a portfolio is crucial. It should go beyond just showcasing final products to illustrating the process of discovery, rapid iteration, and technical implementation in ambiguous scenarios.

💵 Compensation & Benefits

Salary Range: Based on the location (London, UK), experience level (Mid-Level, 2-5 years), and the specialized nature of HCI/AI-focused UX Engineering, a competitive salary range can be estimated. For a Mid-Level UX Engineer in London, salaries typically fall between £55,000 - £80,000 per annum. This range can vary based on specific skills, the company's funding stage, and the candidate's negotiation.

Benefits:

• Competitive salary and potential for equity/stock options in a growing AI startup.

• Comprehensive health and wellness benefits, potentially including private medical insurance, dental, and vision coverage.

• Generous paid time off (PTO) policy, including vacation, sick leave, and public holidays.

• Opportunities for professional development, including conference attendance, training, and access to learning resources.

• Flexible working arrangements, supporting a hybrid work model with remote work options within the UK.

• Pension scheme contributions as per UK statutory requirements.

• Potential for team events, social gatherings, and a collaborative work environment.

Working Hours: The standard full-time working hours are typically 40 hours per week, with flexibility offered within the hybrid work model to accommodate work-life balance.

📝 Enhancement Note: Salary estimation is based on general market data for UX Engineers in London with 2-5 years of experience, considering the specialized nature of the role within an AI startup. Benefits are standard for tech roles in the UK, with an emphasis on professional development and flexibility relevant to this position.

🎯 Team & Company Context

🏢 Company Culture

Industry: Technology / Artificial Intelligence / SaaS

Company Size: The description implies a small, high-talent-density team, suggesting a startup environment. Likely 10-50 employees, focusing on rapid growth and innovation.

Founded: While the founding date isn't provided, the description of building "proactive AI smart assistants" and focusing on "high reliability for long-running workflows" indicates a company in a growth or scaling phase, likely founded within the last 5-10 years to be at the forefront of AI product development.

Team Structure:

• The operations and product development teams are likely small, cross-functional, and highly collaborative, characteristic of a startup.

• Expect direct interaction with founders, lead engineers, designers, and ML specialists.

Methodology:

• Data-Driven Decision Making: Emphasis on using user feedback, performance metrics, and ML insights to guide product development and interface design.

• Agile & Iterative Development: Rapid prototyping, frequent testing, and continuous iteration are central to the workflow, balancing speed with quality.

• High-Talent Density: A focus on hiring exceptional individuals who can operate independently, exercise sound judgment, and contribute significantly across multiple disciplines.

Company Website: https://bjak.my/en/about-us

📝 Enhancement Note: The company description emphasizes a "high talent density" and "hands-on team" that makes "decisions collectively" and moves at "rapid speed." This points to a demanding yet rewarding environment for self-starters who thrive in agile settings.

📈 Career & Growth Analysis

Operations Career Level: This role is positioned as a Mid-Level UX Engineer, requiring a solid foundation in frontend development and a growing expertise in HCI and UX principles. It offers a significant opportunity to shape core product experiences in a nascent AI field.

Reporting Structure: The UX Engineer will likely report to a Head of Design, Lead Engineer, or potentially a Product Manager, with close collaboration across Product, Engineering, and ML teams.

Operations Impact: The UX Engineer will have a direct and profound impact on the usability, adoption, and effectiveness of the AI smart assistant. By crafting intuitive interfaces, they will enable users to leverage AI capabilities more readily, directly influencing user satisfaction, task completion rates, and overall product success.

Growth Opportunities:

• Specialization: Deepen expertise in AI-driven HCI, becoming a go-to specialist in designing for complex AI interactions.

• Leadership: Potential to grow into a Lead UX Engineer or Design Lead role as the team expands, mentoring junior engineers and shaping design strategy.

• Cross-Functional Skill Development: Gain exposure to ML model behavior, product strategy, and rapid iteration cycles, broadening skill sets beyond core frontend development.

• Product Ownership: Opportunity to take significant ownership of key product features and interaction paradigms from conception to launch.

📝 Enhancement Note: The role offers substantial growth potential within a specialized, high-demand field. The emphasis on innovation and ambiguity suggests a steep learning curve and the chance to define best practices in AI interface design.

🌐 Work Environment

Office Type: Hybrid work model, allowing for remote work within the United Kingdom. There may be an opportunity for occasional onsite collaboration in London, but the primary mode appears to be remote or hybrid.

Office Location(s): While the job is posted for London, the remote nature suggests that physical presence in a specific office might not be mandatory daily. The company may have a physical presence in London for key meetings or team gatherings.

Workspace Context:

• A remote-first or hybrid environment that requires strong self-discipline and communication skills.

• Access to modern development tools and collaboration platforms (e.g., Slack, Figma, Jira, GitHub).

• A culture that values asynchronous communication and clear documentation to support distributed teams.

• Opportunities for virtual collaboration and team-building activities to foster connection.

Work Schedule: Standard full-time hours (approx. 40 hours/week) with flexibility. Emphasis on asynchronous work and output, rather than strict adherence to a 9-to-5 schedule, particularly for remote employees.

📝 Enhancement Note: The "TELECOMMUTE" location type and "remote_derived: true" suggest a strong emphasis on remote work flexibility, with London being the primary region of operation or headquarters. The hybrid nature implies occasional in-person collaboration might be beneficial or required.

📄 Application & Portfolio Review Process

Interview Process:

• Application Submission: Candidates are required to submit a portfolio as part of the application.

• Initial Screening: Review of portfolio and resume for fit with technical requirements and HCI focus.

• Round 1 Interview: Likely a technical interview focusing on frontend engineering skills (React, TypeScript) and prototyping abilities.

• Round 2 Interview: Focus on HCI principles, UX instincts, problem-solving, and collaboration style. May involve discussing past projects and design thinking.

• Design Assessment: A practical exercise or take-home assignment to evaluate design and prototyping skills in the context of AI interfaces.

• Final Interview/Team Fit: Discussion with key team members (e.g., founders, leads) to assess cultural alignment and overall fit.

Portfolio Review Tips:

• Showcase Process, Not Just Product: For each project, clearly articulate the problem, your approach, the challenges faced, your specific contributions, and the outcomes. Use visuals and wireframes to illustrate your thought process.

• Highlight HCI & AI Focus: Emphasize projects where you've designed for complex interactions, uncertainty, or AI-driven features. Explain how you approached making AI behavior understandable and controllable.

• Demonstrate Prototyping Skills: Include interactive prototypes (e.g., Figma, Framer) or code examples that showcase your ability to quickly bring ideas to life.

• Quantify Impact: Where possible, include metrics or user feedback that demonstrate the success or usability of your designs.

• Tailor to the Role: Clearly connect your portfolio examples to the requirements of this specific UX Engineer, HCI role at Bjak.

Challenge Preparation:

• AI Interaction Scenarios: Be prepared to discuss how you would design interfaces for AI tasks such as planning, executing multi-step workflows, or handling AI errors.

• Prototyping Tools: Ensure you are proficient with common prototyping tools (Figma, Sketch, Adobe XD) and potentially some code-based prototyping frameworks.

• Explain Your Reasoning: For any design or technical decision, be ready to articulate the "why" behind it, referencing HCI principles and user-centered design.

• Ambiguity and Speed: Practice articulating how you operate effectively in fast-paced, rapidly evolving environments with incomplete information.

📝 Enhancement Note: The interview process explicitly mentions a portfolio requirement and a "design assessment," underscoring the importance of practical demonstration of UX and engineering skills, particularly in the context of AI.

🛠 Tools & Technology Stack

Primary Tools:

• Frontend Framework: React (required)

• Languages: TypeScript (required), JavaScript

• Prototyping: Figma, Sketch, Adobe XD, or similar design/prototyping tools

• Version Control: Git (e.g., GitHub, GitLab, Bitbucket)

• Collaboration: Slack, Zoom, Google Workspace, or similar

Analytics & Reporting:

• While not explicitly stated, the team will likely use analytics tools (e.g., Google Analytics, Amplitude, Mixpanel) to track user behavior and interface performance.

CRM & Automation:

• Not directly relevant to this role, but understanding how frontend interfaces integrate with backend systems and AI services is crucial.

• Familiarity with API integrations and data flow from AI models to the user interface.

📝 Enhancement Note: The core technical stack is clearly defined as React and TypeScript. The emphasis on prototyping and HCI suggests proficiency with design and prototyping tools is equally important. Understanding how these interfaces interact with AI models and backend services is key.

👥 Team Culture & Values

Operations Values:

• User-Centricity: A deep commitment to understanding and serving the user, ensuring AI is helpful, not intrusive.

• Innovation & Experimentation: A culture that encourages trying new approaches, learning from failures, and pushing the boundaries of AI interfaces.

• Collaboration & Transparency: Open communication, collective decision-making, and a willingness to share knowledge and feedback across teams.

• Bias for Action & Execution: A focus on shipping high-quality work at a rapid pace, balancing learning with tangible results.

• Curiosity & Continuous Learning: An intrinsic drive to understand AI, HCI, and emerging technologies, and to constantly improve skills.

Collaboration Style:

• Cross-Functional Integration: Tight integration between Engineering, Design, Product, and ML teams, with minimal silos.

• Iterative Feedback Loops: Regular design reviews, code reviews, and user feedback sessions to ensure alignment and continuous improvement.

• Mutual Respect & Ownership: A culture where team members respect each other's expertise and take ownership of their contributions and project outcomes.

📝 Enhancement Note: The company culture seems to value a blend of agility, intellectual rigor, and collaborative execution. The "high talent density" aspect suggests an environment where individuals are expected to be proactive, self-directed, and contribute positively to team dynamics.

⚡ Challenges & Growth Opportunities

Challenges:

• Navigating AI Ambiguity: Designing interfaces for AI systems where behavior can be non-deterministic and evolving presents a unique challenge in establishing predictability and trust.

• Defining New Interaction Paradigms: Working in a field where established HCI conventions for AI are still emerging requires creative problem-solving and a willingness to experiment.

• Balancing Speed and Quality: Rapid development cycles in a startup environment necessitate making quick decisions while ensuring the user experience remains robust and intuitive.

• Technical Complexity: Integrating cutting-edge AI models with frontend interfaces requires a deep understanding of both domains and effective communication between teams.

Learning & Development Opportunities:

• Deep Dive into AI HCI: Opportunity to become an expert in a rapidly advancing field, shaping the future of human-AI interaction.

• Hands-on ML Exposure: Direct collaboration with ML engineers provides insights into AI model capabilities and limitations, informing interface design.

• Product Strategy Involvement: Influence the direction of the AI product by contributing to feature ideation and user experience strategy.

• Skill Development in Emerging Tech: Gain experience with state-of-the-art frontend technologies and AI integration patterns.

📝 Enhancement Note: The primary challenges stem from the innovative nature of the product and the nascent state of AI HCI. These challenges also represent significant growth opportunities for individuals eager to pioneer new solutions.

💡 Interview Preparation

Strategy Questions:

• "How would you design an interface to clearly communicate the uncertainty or confidence level of an AI's response?" (Focus on transparency, user control)

• "Describe a time you had to prototype a complex user flow with incomplete specifications. How did you approach it, and what was the outcome?" (Focus on rapid prototyping, ambiguity tolerance)

• "How would you design an interface for an AI assistant that needs to perform multi-step tasks, allowing users to supervise and correct it along the way?" (Focus on HCI for AI, user control, workflow management)

Company & Culture Questions:

• "What excites you most about building AI-native interfaces, and what are your biggest concerns?" (Assesses passion and critical thinking)

• "How do you approach collaboration with designers and ML engineers when there are differing opinions on user experience?" (Assesses collaboration style, conflict resolution)

Portfolio Presentation Strategy:

• Tell a Story: For each project, frame it as a narrative: the problem, your role, the solution, the challenges, and the results.

• Show, Don't Just Tell: Use visual aids (screenshots, mockups, live demos, interactive prototypes) extensively.

• Highlight Your Process: Clearly explain how you arrived at your solutions, emphasizing your design thinking and technical approach.

• Focus on Impact: Quantify results whenever possible. If not quantifiable, articulate the qualitative impact on the user experience.

• Be Prepared for Deep Dives: Expect questions about specific technical implementation details, design decisions, and trade-offs made.

📝 Enhancement Note: Interview preparation should heavily emphasize the unique aspects of designing for AI and the hybrid nature of the UX Engineer role, blending technical execution with deep user empathy and HCI knowledge.

📌 Application Steps

To apply for this UX Engineer, HCI position:

• Submit your application directly through the provided link on Ashby.

• Portfolio Customization: Ensure your portfolio prominently features projects demonstrating your frontend engineering skills (React, TypeScript) and your experience with interaction-heavy or experimental interfaces, particularly those related to AI or complex workflows.

• Resume Optimization: Tailor your resume to highlight keywords such as "HCI," "UX Engineering," "React," "TypeScript," "Prototyping," "AI Interfaces," and "User Experience." Quantify achievements where possible.

• Interview Preparation: Practice articulating your design process, technical approach, and how you handle ambiguity. Prepare to discuss specific examples from your portfolio and how they align with the role's requirements.

• Company Research: Familiarize yourself with Bjak's mission and the general landscape of AI assistants. Understand their focus on reliability, context, and real-world task completion.

⚠️ Important Notice: This enhanced job description includes AI-generated insights and operations industry-standard assumptions. All details should be verified directly with the hiring organization before making application decisions.