Staff/Lead Software Engineer, Mobile/Frontend

Belfry; New York (NY); On-site; USD 150,000 - 210,000; Full time

Benefits offered by this job

Competitive salary

Equity in startup

Healthcare (medical, dental, vision)

Unlimited PTO

11 paid holidays

Job summary

Belfry is seeking a Lead Mobile / Frontend Software Engineer to own the React Native / Expo mobile app and help set engineering standards as we scale. You will shape both mobile and frontend architecture, own the user experience, and grow into a team leadership role.

You’ll influence best practices, contribute across the stack, and advance secure, performant software across mobile and web platforms. This is a full-time, on-site role in New York.

Qualifications

• 5+ years of experience as a software engineer.
• Strong expertise in React and React Native with Expo.
• Experience owning frontend/mobile projects end-to-end.
• Ability to mentor engineers and lead a team over time.

Responsibilities

• Own and evolve Belfry's mobile app built on React Native / Expo and extend standards to the web platform.
• Set UI standards, best practices, observability, and design systems across mobile and web.
• Contribute across the full stack when needed, including APIs and backend services.
• Deploy and scale systems with security, reliability, and performance in mind.
• Champion AI-assisted coding practices to improve developer productivity.

Skills

React

React Native

Expo

Frontend architecture

Team leadership

UI/UX

Job description

At Belfry, we’re changing how the $50 billion Security Guard Services industry operates. Our mission is simple but ambitious: to empower both back-office teams and field officers with the tools they need to excel through our state-of-the-art operating system.

We’re looking for a Lead Mobile / Frontend Software Engineer to take ownership of our React Native / Expo mobile app and help set the engineering standard across our frontend stack as we scale. This role is ideal for someone who wants the full early-stage startup experience: shaping our mobile and frontend architecture, owning the user experience across our React Native app and web platform, and growing as a subject matter leader on the team.

What You’ll Accomplish

• Own and evolve the mobile app built on React Native / Expo, ensuring field officers have reliable, performant tools in their hands every shift, and extend that same standard of quality to our React web platform.
• Set the standard for how we build UI — establishing best practices, observability, and design systems across mobile and web that the rest of the team rallies around.
• Contribute across the full stack when needed — whether that’s building an API endpoint, debugging a backend service, or wiring up a new integration.
• Deploy and scale systems using industry best practices to ensure secure, available, and performant software.
• Champion agentic development workflows — help the team adopt and get the most out of AI-powered coding tools, making everyone faster and more effective.

About You

• Strong communicator: You can clearly explain your ideas and views on everything from technical architecture to product design.
• Ownership-focused: You’re excited to work in an environment where you have a high degree of responsibility for the product and a hand in shaping Belfry as a company.
• Team-driven: You see work as a collaborative endeavor — you value growing in your role while helping those around you grow as well. You’re energized by mentoring other engineers and eventually leading a team.
• Deep React expertise: You have multiple years of hands-on experience building with React and ideally React Native + Expo. Other mobile development experience (Swift, Kotlin, Flutter) is a plus.
• UX-minded: You care about the craft of building great interfaces — not just that it works, but that it feels right for the people using it.
• Comfortable across the stack: You have deep expertise in the frontend, but you’re not afraid to dive into backend code, APIs, or infrastructure when the team needs it. Familiarity with Python is a bonus.
• Technically strong: Typically 5+ years of experience as a software engineer, with a track record of owning complex mobile or frontend projects.
• Always learning: You bring an open mindset to your craft — you’re not tied to one framework, you pick the right tool for the job, and you’re actively exploring how AI coding tools are changing the way software gets built.

Benefits

• An incredible team with fantastic experience and track record
• Highly competitive salary
• Significant equity in a high-growth startup with a clear path to significant outcomes
• Fully covered healthcare, dental, and vision
• Unlimited PTO (and strong encouragement to use it!) plus 11 paid holidays