Founding Engineer · In-Office · Mid-level · Summer

Sunspell is a venture lab, and this is a founding engineering seat. You build and ship end to end across our internal operating system and the products on top of it, from prototype to production, with AI agents and models as a default part of your toolkit. You care how the product feels as much as whether it runs. That range is the point.

Most of your time is on our own products, with the occasional studio project.

• Build features and infrastructure across our operating system and the products on top of it.
• Take prototypes to production and own their quality, performance, and reliability.
• Build with AI agents and automations as core infrastructure, not novelty.
• Create reusable systems and tooling that make the next build faster.
• Work closely with designers to ship end to end.

• Seven or more years shipping software, versatile across the full stack rather than siloed in one area, with production code you have personally shipped or handed off within the last year.
• Strong product sense. You understand product and shipping, and you stay open to features that look unnecessary now and prove vital later.
• Applied experience with LLMs, vision and voice models, and the evaluation systems that make them reliable.
• Solid engineering discipline: test-driven development, QA, some Dev Ops, and security fundamentals. We work in a lean-startup, Scrum-style rhythm.
• You ship production-ready systems, with good judgment and an eye for the details.
• Comfortable with early-stage ambiguity and a bias to ship.

• React, Tailwind, Type Script, and Node.js, deployed on Cloudflare.
• AI tooling: mostly Claude Code, plus Open Code and Codex.
• We build a lot of MCP servers, and we use Git Hub throughout.
• You do not need our exact stack on day one; strong engineers ramp fast.

• Harness engineering and context engineering for production AI agents are a huge plus. We build a lot of agents, so experience designing the scaffolding, tool loops, memory, evaluations, and context systems around models is especially valuable.
• Three.js and particle systems.

You do not have a perfect resume, a famous logo, or a specific degree. We care more about what you have built, how you think, and how fast you learn. If your ability is ahead of your title, apply anyway.

• Ship meaningful features across our operating system or a product.
• Stand up at least one reusable system or workflow the team adopts.

The front door is not the ceiling. Strong engineers grow into leading the platform or the technical direction of a product, with a path to run one they help prove out.

• Location. New York, in person, full-time.
• Setting. Full-time. For the right person we go straight to a full-time offer.
• Level. Senior, seven or more years shipping software.

Ownership. You should own a piece of what you build here. We are not going to post a percentage, because the honest answer depends on what you end up carrying, and we would rather work that out with you than hand you a number that pretends to be precise. It is a conversation, it is flexible, and we intend it to be fair.

Benefits include health coverage, top-tier equipment, the tools you need, and a learning budget. Full terms are in the offer.