Founding Design Engineer

About the Role

You'll own the design and development of Sim’s visual, agent-building platform—the canvas where developers build, connect, and launch AI agents. From architecture to polished interactions, you'll define how thousands of developers visually create with Sim. Your work blends UI/UX design with engineering, shaping the interface, experience, and real-time systems at the heart of our product.

Sim has been called "Figma for AI agents," and you’ll push this further—making our canvas more powerful, delightful, and performant as workflows grow. You’ll partner with engineering, design, and product to deliver a seamless agent-building journey from initial creation through to production.

This is a foundational role. You’ll set standards across visual design, interaction patterns, and UI responsiveness. On our lean team, you’ll influence everything the user interacts with and rapidly ship features that impact thousands.

What You'll Do

• Own the design and development of Sim’s visual canvas—the real-time, drag-and-drop editor central to our platform

• Architect and implement intuitive UI systems for complex agentic workflows

• Shape how developers interact: design, test, debug, and deploy agents seamlessly within the product

• Ensure the experience remains fast, beautiful, and robust as workflows grow in size and sophistication

• Bridge visuals and execution: what users see is what runs

• Set standards for front-end code, component architecture, design systems, and user ergonomics

• Collaborate across the stack in our Next.js monorepo; ship to production daily

• Define and refine UX/UI patterns, with attention to developer delight

What We’re Looking For

• Design-minded engineer with deep experience in React and TypeScript

• Strong UI/UX intuition—you care how things look and feel, not just how they work

• Experience building complex, interactive frontend systems (canvas editors, collaborative tools, visual builders, etc.)

• Proven ability to deliver polished, user-focused developer or creative tools

• Deep understanding of front-end performance, animation, and responsiveness

• High agency and ownership—help define the roadmap as well as build it

• Comfort working in Next.js; backend experience is a plus

• Experience with real-time systems (WebSockets, CRDTs, etc.) is a plus

• Visual design skills or open-source contributions are a plus

Why Sim

• Foundational impact. Shape the design DNA of Sim and influence the future of how agents are built.

• Real users, real scale. 70,000+ developers use Sim—your work matters immediately.

• World-class backers. Series A led by Standard Capital, with Paul Graham, Perplexity, SV Angel, and Y Combinator.

• Open source from day one. 26,000+ GitHub stars and an active builder community.

• Competitive salary + meaningful equity. Early team, significant ownership.

• Full benefits. Comprehensive health insurance and relocation support.

• Visa sponsorship available.

Equal Opportunity

Sim is committed to creating an inclusive environment for all employees. We celebrate diversity and are committed to creating an inclusive environment for all team members. We do not discriminate on the basis of race, religion, color, national origin, gender, sexual orientation, age, marital status, veteran status, or disability status.