Sr. Backend Engineer

$230,000 - $280,000  (Open to Staff leveling at $280-330K)
Full-time / Onsite (5 days/week)

About The Role

At Mochi, our engineering team operates with exceptional leverage. We believe in high talent density, where a focused, elite team powers a profitable, nine-figure ARR healthcare platform serving hundreds of thousands of patients. We are looking for a Senior Backend Engineer to own the core systems that power this scale—from clinical approval workflows and multi-pharmacy fulfillment routing, to complex subscription billing and partner integrations.

Mochi has already helped patients lose over 5 million pounds through metabolic care, and we are now rapidly expanding into the frontiers of preventative healthcare—including hormone optimization (HRT/TRT), longevity medicine, and cutting-edge peptide therapies. The backend systems you architect will power how this next wave of patients discovers treatments, qualifies for care, and receives highly personalized, dynamic dosing protocols.

Because of our high scale-to-team ratio, we do not operate in isolated technical silos. You will own your systems end-to-end: designing the schema, writing the business logic, deploying to Kubernetes, and owning the observability in production. If you are drawn to architectural problems where the domain complexity is real, the autonomy is absolute, and the impact on patient outcomes is tangible, this is the role.

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.
• If you are targeting Staff leveling: We expect a demonstrated track record of setting technical direction across teams, navigating deep ambiguity, and measurably leveling up the engineers around you.

Our stack is 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.

Our Process

We respect your time. Here is exactly what to expect:

1. Intro call (30 min, remote) — Chat with our recruiter about the role and expectations.
2. Hiring manager screen (45 min, remote) — Technical background, motivation, and what you're looking for.
3. Technical round (2.5 hrs, remote) — Practical coding (AI tools welcome) + system design conversation. Real problems, not LeetCode.
4. Team meet (2 hrs 15 mins, on-site) — Come to our SF office to meet your future manager, engineering peers, and product partners for 30-minute 1:1s, concluding with a quick recruiter wrap-up.

We are ready to move as fast as you are. Total interview time is ~6 hours. We can go from the first intro to offer in two weeks, or pace the rounds to comfortably fit your current work schedule.

Life at Mochi 

At Mochi, we believe your best work happens when you feel your best—so we’ve designed an environment that fuels your creativity, supports your growth, and makes every day exciting.

🥗 Daily Meals and Espresso Bar - Breakfast, lunch, and dinner every weekday. Our on-site barista keeps the espresso and matcha flowing all day

💰 Pre-Tax Commuter Perks - Save on transit and parking through pre-tax commuter benefits

💸 Top-of-Market Compensation - We offer competitive salaries along with generous equity packages so you can share in the success you help create

💣 Profitable and Rapid Growth - We’re scaling fast, with financial discipline and long-term vision. No VC constraints, just sustainable momentum and smart decisions

🚀 High-Impact Work - Help shape the future of digital healthcare. Your work here directly improves lives and scales nationwide

👩‍💻 World-Class Team - Collaborate with teammates from Tesla, SpaceX, Citadel, Harvard, IIT, and more. We value excellence, humility, and empathy in equal measure

✨ Comprehensive Benefits - 401(k) with match, generous time off, life insurance, and high-quality medical, dental, and vision plans

💊 Mochi Health Membership – We cover your monthly subscription fee so you can experience the same care as our patients (medications not included)

🌴 Time to Recharge –Enjoy unlimited PTO, generous company holidays, and true flexibility. We trust you to take the time you need to rest, reset, and thrive

🧘 Wellness First –From weekly mindfulness sessions to group workouts and fitness perks, your physical and mental health are top priority

🎉 Team Socials and Community - We make time to connect through regular socials, happy hours, and spontaneous events. Our stocked kitchen doesn’t hurt either

📍 Downtown SF HQ - Our San Francisco office is just steps from BART, Muni, and great food. It’s designed for deep work and casual collaboration

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The base salary for this full-time position ranges from $230,000 to $280,000, in addition to equity and benefits. The salary range listed in each job posting represents the minimum and maximum targets for new hire salaries across all locations. Actual compensation within this range is determined by various factors, such as job-related skills, experience, relevant education or training, and location.

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