Senior Back End Engineer

About Zello

Zello is a voice-first communication platform, powered by our industry-leading push-to-talk technology, to improve collaboration and productivity for desk-less workers. With over 175+ million users, we’re the #1 rated push-to-talk app in the world, delivering 9 billion (yes, with a B) messages a month.

At Zello, our company values are at the heart of what we do every day. We’re proud to serve the frontline, we’re privileged to connect people in times of crisis across the globe, and we’re honored to support first responders.

And this is where you come in.

What You'll Do

• Operate as a senior individual contributor on the backend services team, owning production for distributed systems at real-time scale.
• Carry the on-call rotation for Zello's most critical infrastructure. Lead incident response, write runbooks, and turn each incident into a durable improvement.
• Build observability where it's missing. Set SLOs, instrument services with Grafana and Loki, and shift team posture from reactive to proactive.
• Ship production C++ today; contribute to Rust and Go components as they come online.
• Work hands-on across our database stack: Cassandra, MongoDB, MySQL and choosing the right tool for the workload.
• Contribute to backend 2.0: a ground-up modernization of the platform anchored on AI-native engineering workflows (AGENTS.md, CLAUDE.md, .cursor/rules).

Who You Are

• You've carried real production weight on distributed systems at scale, and you talk about reliability as something you own, not something you measure.
• You've shipped C++ in production for years and read long-lived backend codebases without flinching. Rust or Go in your toolkit is a plus.
• You've gone deep on at least one of Cassandra, MongoDB, or MySQL, and can name the tradeoffs because you've felt them in production.
• You use AI-assisted development as a default and have shaped CLAUDE.md, AGENTS.md, .cursor/rules, or equivalent for a real team.
• You thrive on a small team where every hire moves the needle. You drop ego in code review. You take scope, you don't wait for it.
• Your definition of "done" includes tests, alerts, observability, and runbooks.

This Role Is Not

• A management or tech-lead-without-keyboard role. The team is three people and you're shipping production code week one.
• A pure greenfield architect role. Backend 2.0 is real, but reliability and ops on existing critical services come first.
• A "ship your AI tooling and call it a day" role. AI-native posture is the floor, not the ceiling.
• A role with layers of approval between idea and ship.