Design Engineer in London

About HASH

At HASH, we're building infrastructure to solve information failure and help everybody make the right decisions. Our open-source platform helps organizations turn fragmented information into typed, temporal knowledge and process graphs that support analysis, simulation, optimization and automation. We're building towards world models from a different starting point from most AI labs: explicit representations of real systems, the entities within them and the processes through which they change.

About the role

We're hiring a Design Engineer to design and build the interfaces through which people understand and act on complex systems. This is a hybrid design and engineering role. You will take problems from ambiguity to shipped software: understand the user and underlying system, explore interaction models, establish the visual structure, prototype quickly, test the important assumptions and implement the final experience in production-quality React and TypeScript.

HASH is not a conventional CRUD application. Our interfaces need to make dense, changing information understandable: knowledge graphs, process models, timelines, simulations, provenance, uncertainty, AI actions and collaborative edits. The challenge is not simply to make those systems look attractive. It is to find interaction paradigms that let people inspect them, manipulate them and develop an accurate mental model of what is happening.

From time to time, you'll also work on HASH's digital brand expression. That may include building a product launch page, an interactive explanation of a technical idea, a polished demo, a new website section or a reusable visual component that works across product and marketing. You should care equally about the quality of a workflow used every day and the first few seconds in which someone encounters HASH.

The balance will usually be weighted towards product work—roughly two-thirds product and one-third brand/web—but will vary according to what is most important. You will work directly with product designers, engineers, researchers, customer-facing colleagues and HASH's founder. As our design and marketing teams grow, you will help define the systems and standards through which their work becomes real.

This is not a conventional design role in which finished Figma files are handed to an engineering team. You should want to own the implementation. It is also not a conventional frontend role in which somebody else has already decided what to build. Your design judgment is the reason for the role.

Requirements

• A visual portfolio showing exceptional product and interaction design, including substantial work that you personally implemented
• Strong visual craft across typography, layout, spacing, hierarchy, color, states and motion
• Production-level ability with React, TypeScript, HTML and modern CSS
• Experience designing and building responsive, accessible interfaces from rough requirements rather than detailed specifications
• The ability to reduce a complicated domain or workflow to a clear interaction model without hiding important truth
• Strong prototyping instincts: you know when to sketch, use Figma, build a throwaway coded prototype or work directly in the production codebase
• Experience creating or extending design systems, component libraries and reusable interaction patterns
• Comfort moving between product UX, frontend architecture and brand/communication design without treating any of them as someone else's problem
• The ability to work closely with engineers on data models, APIs, state, performance and technical constraints
• High agency, pace and attention to detail; you notice weak decisions and unfinished edges and take responsibility for resolving them
• Excellent written and spoken English and the ability to explain the reasoning behind your work clearly
• You do not need a particular degree, and we do not care whether you began your career in design or engineering. We care whether you have developed both sets of capabilities to a genuinely high level.
• Experience with data visualization, graph interfaces, diagramming tools, multiplayer applications, developer tools, AI products, simulation software or other information-dense systems is particularly relevant. So is experience with SVG, Canvas, WebGL, animation, creative coding, design tokens, Storybook, Next.js or open-source software.

What you'll do

• Design and implement solutions end-to-end: from UX wires and experimentation, through to in-app delivery and interaction design polish
• Work with users, customer-facing colleagues and product teams to understand workflows, failure modes and real constraints
• Design and build interfaces for knowledge graphs, process models, simulations, AI-assisted workflows and complex operational data
• Develop clear ways to navigate entities, relationships, state changes, provenance, uncertainty and history
• Prototype alternative interaction paradigms and test them before the team commits to an approach
• Ship polished production interfaces in React and TypeScript, including the final details that are often lost between design and implementation
• Build and maintain accessible, responsive components and patterns that work coherently across HASH
• Improve our design system, design tokens, component APIs and the collaboration model between design and engineering
• Create coded brand and marketing experiences, including landing pages, interactive explainers, product announcements and demonstrations
• Translate HASH's visual identity into motion, interaction and reusable web components
• Work with brand and marketing colleagues on assets that become more compelling because they are interactive rather than static
• Use AI-assisted design and coding tools thoughtfully to explore more possibilities and ship faster, while retaining responsibility for every decision and line of production code
• Review the product regularly, identify quality gaps and fix them without waiting for a perfectly formed brief
• Contribute reusable work to HASH's open-source codebases

Why HASH

• Work on interaction problems that do not already have standard answers
• Design for graphs, processes, simulations and AI systems that model consequential parts of the real world
• Move directly between an idea, a design and the production implementation without a handoff boundary
• Shape both the product experience and the digital expression of the HASH brand
• Work closely with the founder and a deeply technical product, engineering and research team
• Contribute to open-source software and establish patterns that other people can build upon
• Join at a moment of rapid growth, with unusual ownership and influence over what HASH becomes
• Be part of a high-agency team that cares about output, ownership and quality

Benefits

A base salary will be offered of £90,000-130,000 in London. In addition, you'll receive generous equity on top of your base salary, in order to align incentives.