Software Engineer, Frontend

Sim•San Francisco, CA

5d•Onsite

About The Position

Sim is building the leading platform for AI agents—enabling developers and enterprises to visually create, launch, and manage high-performing agents that automate the world’s workflows. Our mission is simple: agents will run the world, and Sim is the primary means by which that happens. We’re backed by world-class investors including Standard Capital, Paul Graham, Perplexity, SV Angel, and Y Combinator, and we’ve been open source from day one. We're a small, fast-moving team based in San Francisco, building together in person every day. 70,000+ developers use Sim; your work ships fast and impacts real users at scale. We believe in ownership, excellence, and ambitious builders shaping the future from the ground up. As a Software Engineer, Frontend at Sim, you'll own the development of our agent-building canvas and frontend platform. You’ll architect intuitive user experiences, build robust and high-performance UI components, and help define how thousands of developers create with Sim. Working with engineering, product, and design, you’ll deliver features from concept to production, directly shaping our product’s design, performance, and developer experience.

Requirements

Deep experience in React and TypeScript
Strong intuition for UI/UX design and developer experience
Proven ability to build complex, interactive frontend applications (canvas editors, visual builders, collaborative tools, etc.)
Understanding of frontend performance, animation, and real-time systems (WebSockets, CRDTs, etc.)
High agency and ownership mentality—drive features from ideation to launch

Nice To Haves

Experience with design systems
Experience with Next.js
Open-source contributions

Responsibilities

Architect and develop key frontend systems, focusing on visual, interactive experiences that empower users to build and manage AI agents
Lead the implementation of new features, UI components, and real-time interactions in a Next.js monorepo
Ensure the frontend experience is performant, polished, and delightful at scale
Set standards for front-end code, UI architecture, and design systems
Collaborate with engineering, design, and product teams to deliver seamless developer workflows
Extend our custom component library, and extend our existing design system
Prototype and iterate rapidly, shipping high-impact improvements daily