Sr. Backend Engineer

What You’ll Do

• Architect Healthcare Commerce: Build and evolve a subscription and billing infrastructure that handles the messy reality of healthcare. You will solve for mid-cycle medication switches, dynamic pricing across different pharmacy partners, payment recovery, and prorated billing.
• Build Clinical State Machines: Own the systems that power complex medication ordering and fulfillment. You will build highly reliable pipelines that handle compounding pharmacy integrations, controlled substance compliance, and personalized dosing protocols across a distributed network of external partners.
• Own the Infrastructure: Take hands-on ownership of the AWS and Kubernetes infrastructure that runs your services. You will establish CI/CD pipelines, build observability, and create deployment patterns that make it safe for the entire team to ship rapidly.
• Act as a Product Partner: Work directly with Clinical, Operations, and Product teams to shape what we build. You will evaluate proposed workflows, take ownership of business outcomes, and actively identify paths to deliver maximum patient value with highly efficient implementation.
• Build Agentic Workflows: Mochi is an AI-first engineering org. You will not only utilize frontier agentic models to accelerate your own development, but you will also design the backend architecture that allows AI-assisted agents to automate clinical operations, improve patient safety, and scale our provider workflows.
• Raise the Engineering Bar: Own key architectural decisions, systematically upgrade legacy systems, and elevate the engineers around you through rigorous code review, testing practices, and technical standards.

Who You Are

• You have operated high-stakes systems. You have 5-7+ years of backend engineering experience. You've built and operated production systems that handle real complexity—not just high traffic, but complex domain logic, distributed stateful workflows, and deep integrations with external partners.
• You get data modeling right. You think carefully about schema design, state transitions, and domain boundaries, because you've seen what happens downstream when the foundational model is wrong.
• You are an infrastructure owner. You are comfortable with (or eager to master) Kubernetes, Terraform, AWS, and CI/CD, and you view deploying your own code and owning your system's reliability as a fundamental part of backend engineering.
• Your workflows are altered by AI. You are already using frontier agentic tools (e.g., Codex 5.3, Claude Opus 4.6) to build faster. You can describe specific ways these models have structurally changed how you code, while retaining the deep technical skepticism required to audit, verify, and own its output.
• You are a collaborative builder. You have low ego, high standards, and excellent communication skills. You thrive in cross-functional environments where engineering requirements are heavily shaped by healthcare regulations, compliance, and patient safety.
• You are excited to work in-person. You want to build alongside the team 5 days a week in our San Francisco office.

Our stack: TypeScript, Node.js, Express, PostgreSQL, Redis, Kubernetes, Terraform and AWS. Experience with these is a strong plus, but we index on engineering fundamentals, distributed systems experience, and domain reasoning over language-specific syntax.