This is an exciting opportunity to join an early stage company of talented engineers and designers, led by seasoned climate tech veterans. At Zero, Senior Engineers are individual contributors that report to a Lead Engineer. You will work in small teams (1 designer and 1-2 programmers) in six-week cycles, to take loosely defined projects and deliver new features. Senior Engineers are given broad latitude to make project-level design decisions and expected to operate effectively with minimal oversight. We are relentlessly focused on sustainable productivity. You should expect long stretches of deep work, minimal standing meetings, effective in person collaboration with stakeholders and peers, as well as flexibility around your personal life.

Our Senior Mobile Engineer will build the future of our consumer mobile app, which enables homeowners to get a design and quote for their HVAC project without an in person sales visit. The mobile app is our most important digital touchpoint with homeowners, and you will own features end-to-end on both iOS and Android. Today the app is built fully native with SwiftUI and Jetpack Compose, and the groundwork has been laid for rapid iteration and innovation.

You are fluent on both iOS and Android. You may be stronger in one than the other, but you can confidently navigate both platforms, understand the frameworks, and ship production features in Swift and Kotlin. You have at least 5 years of professional software engineering experience, with meaningful time spent building native mobile applications that real users rely on.

You have strong opinions about AI in the mobile development loop. Agentic coding tools - Claude Code, Cursor, Codex, and whatever comes next - are a core part of how you work. You have a point of view on which problems they're great at, where they fall down, and when to keep a human in the loop on review and verification. You treat your AI toolchain the way a craftsperson treats their workshop: opinionated, evolving, and always sharpened.

You are relentlessly customer-centric. When a real user hits a bug, you want to know immediately, and you are happy to drop your in-flight work to unblock them. You see customer-reported bugs as the most important signal you get, not a distraction from your roadmap. Production problems are part of the job, not an interruption to it.

You have a strong bias toward shipping and learning. You know the difference between recklessness and accepted risk, and you are comfortable weighing the severity of one user's problem against the benefit to everyone else. When the call is hard, you make it and move - you don't wait for certainty that may never come.

You care deeply about observability. Before a feature ships, you know how you'll measure it - what events you'll instrument, what dashboard you'll watch, and what the signal looks like for "working" vs "broken." You have experience with a product analytics platform (we use PostHog) and you view a live, populated dashboard as the reward for what you've built, not a follow-up ticket.

You are enthusiastic about in-person work and collaborating with your colleagues in front of a whiteboard. You live within 50 miles of Denver, CO or are willing to relocate.