Fullstack Software Engineer (AI-Native)

Fullstack Software Engineer (AI-Native)

Cambridge, MA

About Us

Proton is building the AI operating system for wholesale distribution, embedded in the workflows that move nearly every physical product on the planet. Distribution is a $9 trillion industry, and the software that runs it has been stuck in the past for decades — most tools create more work than they eliminate. We unify CRM, PIM, eCommerce AI, and Order & Quote Entry AI into one platform with one data layer and one AI brain, so reps spend their time deepening customer relationships, not entering data.

We hire people with high agency and high urgency. At Proton, everyone is a builder who owns problems end to end and ships AI-native software faster than anyone else in the category.

The median Proton customer reports 3x profit return per dollar spent, an extra day of sales per rep per month, and "the best ROI of any tech investment in 30 years." Hundreds of leading distributors — from family-owned shops to publicly-traded enterprises across, industrial, HVAC, electrical — run on Proton. We're backed by Felicis Ventures (Twitch, Shopify, Opendoor) and Battery Ventures.

If you want to build the systems that shape how trillions of dollars of physical goods move through the economy, Proton is the place to do it.

The Role

We're hiring a Senior Fullstack Engineer to ship products end-to-end across our CRM platform for distributors. This is a generalist role: any layer of the stack, any type of work — frontend, backend, data, integrations — wherever the user impact is. You'll work closely with PMs, designers, and other engineers to scope, build, and deploy features that distributors feel directly. Periodically, you'll work directly with customers to support onboarding, troubleshoot integrations, and help distributors get the most out of the platform. You'll be the person who can sit with a customer's IT team, understand how their ERP is configured, and translate that into something Proton can work with. Expect occasional travel to customer sites a few times a year.

Two things make this role different from a standard fullstack opening:

1. You're an AI-native operator, not a code writer. Every engineer at Proton uses Claude Code (and other agentic dev tools) as a first-class collaborator. We expect features to be designed, built, reviewed, tested, and shipped with heavy AI leverage. You should already work this way — guiding agents, structuring context, validating output, and making judgment calls AI can't.
2. You're a generalist by default. We don't silo engineers into "frontend only" or "backend only." When a feature needs a Vue component, a Python handler, a Postgres migration, an Airflow DAG, and an ERP integration, you're expected to handle all of it — with AI doing the typing and you doing the thinking.

Location: Boston-based. Hybrid, 3 days/week in our office at Harvard Square, Cambridge.

Compensation: $150k – $200k base salary, depending on experience. Includes equity and full benefits.

What You'll Do

- Own end-to-end delivery of features — from refining tickets to deployment, monitoring, and iteration.

- Operate AI coding agents (Claude Code and similar) at a high level: scope work, structure context, run multiple agents in parallel where it makes sense, and ship reviewed, production-quality output.

- Move fluidly across the stack — TypeScript/Vue on the frontend, Python on the backend, SQL and data modeling, infra touchpoints. Pick up whatever the work needs.

- Collaborate in a squad model with PMs, designers, and engineers; participate in 2-week sprints, standups, refinements, retros, and code reviews.

- Design schemas, queries, and APIs that hold up at scale — performance, reliability, and correctness are on you, not on the agent.

- Contribute to engineering practices: better patterns, better tooling, better ways to use AI across the team.

- Spend time with customers onsite a few times a year — distributors operate in warehouses and on sales floors, and the best product calls come from being there in person.

Requirements

- 5+ years as a software engineer with real, demonstrable fullstack delivery — production systems, real users, real ownership. Resume-level hands-on experience, not LLM-generated portfolios.

- Strong fundamentals. You understand what the code is doing and why. You can read a stack trace, reason about a query plan, debug a race condition, and tell when an agent is wrong. We are explicitly not hiring "vibe coders" who depend on AI to compensate for missing fundamentals — AI amplifies seniority, it doesn't replace it.

- Daily, hands-on use of agentic dev tools. Claude Code, Cursor agent mode, Codex, or equivalent — used to ship real features, not just autocomplete. You can talk concretely about how you structure prompts, manage context, parallelize agents, and verify their output.

- Generalist instinct. You're comfortable jumping between Vue, Python, SQL, infra, and integrations. You don't wait for someone else to take the layer you're "not assigned to."

- Database and systems chops. You design efficient schemas and queries, understand indexing and tradeoffs, and can reason about distributed-system failure modes.

- Startup mindset. Pragmatic, fast, biased to ship, comfortable with ambiguity, close to users.

- Strong communication. You can explain technical decisions to PMs, designers, and customers — in writing and in person.

- Ownership and judgment. You take features from idea to production and exercise good taste on what to build, what to cut, and when AI output isn't good enough.

Big Plus

- Experience building integrations with distribution ERPs (Epicor Eclipse, P21, or similar) — ingesting orders, products, customers, pricing; reconciling messy real-world data. Bonus if you've done this in a customer-facing or implementation context.

- Experience building or integrating with agentic products — MCP servers, tool-using agents, agent frameworks, evals, prompt/context engineering at the system level.

- Prior experience at an early-stage SaaS startup.

Benefits

- Competitive salary + company stock options — we want you to feel like an owner.

- Flexible schedule with high autonomy.

- Unlimited PTO + 10 company-paid holidays.

- 12 weeks fully paid parental leave (primary and secondary, including adoption and fostering).

- Annual company-paid offsites.

Proton.ai participates in the E-Verify program: Notice of E-Verify Participation, Right to Work.