Principal Design Engineer

Role: Principal Design Engineer

As Principal Design Engineer (and first Design Engineer), you’ll sit at the core of the product and company, shaping how users interact with fiveonefour—especially through product UX and GUI.

What you’ll do

• Own and improve developer-focused UX with strong visual and interaction design instincts (spacing, hierarchy, delight, etc.).
• Ship code as a design engineer, accelerating the product team by combining design judgment with implementation.
• Run a rigorous, user-driven design process: discovery, validation, iteration, and delivery.
• Produce end-to-end outputs including:
  • Wireframes, journey maps, interaction flows, and high-fidelity visual designs
  • Prototyping and iteration in code with production-ready feature delivery
• Treat design systems as a force multiplier, helping build and scale the system.
• Extend beyond GUI into programmatic and adjacent surfaces, including:
  • APIs and CLI
  • Brand, marketing, and onboarding
• Work across both MooseStack (open source agent harness) and the commercial hosting platform.
• Start as an individual contributor, with the opportunity to coach/mentor the designer on the team and potentially lead the function as the company grows.

Reporting line

• Reports to the Co-founder / CPO and works closely with the founding team on product decisions.

Requirements / skills (implied)

• Strong product UX and visual design taste and attention to detail.
• Ability and willingness to build what you design (hands-on coding).
• Deep empathy for developers and opinions about what great DX (developer experience) feels like.
• Experience designing with user-driven discovery/validation/iteration.
• Understanding and ability to help build design systems.

Nice-to-haves (implied)

• Experience spanning both GUI and programmatic interfaces (APIs/CLI).
• Experience with design systems at scale.
• Potential interest in leading the design function as it grows.