Senior Full Stack Software Engineer

About Underline Underline starts with our people. At Underline, we've rapidly built a culture around ownership, trust, community, and innovation. Underline is dedicated to cultivating a growth environment where people feel valued, work with a purpose of mission, and are professionally challenged. Are you ready to join this team and transform U.S. communities? Underline was founded in 2019 with a singular mission: to deliver modern connectivity infrastructure as the foundation for flourishing communities. With an ethic of partnership, Underline deploys multi-purpose fiber networks to power community goals. These networks deliver ultra-fast internet access to every part of a community—from homes to small businesses, non-profits, enterprise clients, school districts, and governments. Our first two projects are in Colorado Springs and Fountain, Colorado. About this Position Underline is seeking a Senior Full-Stack Engineer to join our small team building the software that runs a fiber network business. This is a Senior role in the real sense. You will write the specs and technical design documents, not receive them. You will carry projects from a business conversation to production. This position uses agentic coding tools daily, with the same review discipline you would apply to a strong junior teammate’s pull request. This is a U.S. Based position, travel to quarterly off-site company retreats is required. What You'll Own Features, end to end. You take work from a loosely defined business need through design, implementation, deployment, and monitoring. Nobody hands you a spec. You write it and defend the tradeoffs in it. Sometimes the right answer is that the whole thing should be smaller, and we expect you to say so.AI-assisted delivery. You use Claude Code as a core part of how you work: decomposing problems so agents make real progress, running parallel threads when that helps, and reading every diff before it lands. You also improve how the team does this, from the CLAUDE.md files and MCP servers to the gates that make agent output safe to trust.The stack. Backend services in Go, event-driven integrations over NATS, GraphQL and REST APIs, and the Ember front-end that consumes them. You care what the screen looks like and how it feels to use.The quality bar. Tests, CI/CD, observability, and performance are your responsibility, not a separate team’s. The more code agents generate, the more this matters.The team. You make pragmatic calls under ambiguity, write down the patterns worth repeating, interview candidates, and make the engineers around you better with these tools. Does this sound like you? You would rather own an outcome than be handed a task.You can walk someone through code you shipped last month and explain every decision in it, whether you typed it or an agent did.You know when good architecture is worth the delay and when it’s not, and you make that call yourself.You like early-stage environments, which means some of your work will be thrown away.You work well alongside product managers, designers, and network engineers and know how to have meaningful productive conversations.You want to work on infrastructure that strengthens American communities and makes access more equitable. Experience we’re looking for 8+ years of professional software engineering experience, including production ownership across the stack.Current, demonstrated practice with agentic coding tools.Deep expertise in Go and strong command of PostgreSQL, including schema design and query optimization.GraphQL and REST APIs in production, plus TypeScript and a modern front-end framework (Ember, React, Vue) and a utility-first CSS framework like TailwindCSS.Docker and Kubernetes in production, and event-driven architectures on a message system such as NATS, Kafka or RabbitMQ.Test-driven development and CCI, plus a solid grasp of web security, authentication and authorization.Strong debugging across distributed systems including code you did not write. Bonus points Experience in telecom, broadband, or infrastructure companiesLocal to the Dallas, TX area