Software Engineer, Frontend

About Sim

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.

About the Role

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.

What You'll Do

• 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

What We’re Looking For

• 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

• Experience with design systems, Next.js, and open-source contributions is a plus

Why Sim

• Foundational impact shaping Sim’s product and frontend architecture

• Immediate scale: your work reaches 70,000+ developers

• World-class team and investors

• Open source culture with 26,000+ GitHub stars

• Competitive compensation and meaningful equity

• 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.