Principal Engineer, Fin AI Agent

What's the opportunity?

Fin is the #1 AI agent for customer service. It resolves over 1M customer conversations every week, and we're just getting started. We're on the cutting edge of defining how AI agents should work — inventing paradigms that didn't exist six months ago and discovering entirely new problem spaces every time we push the technology further.

This role sits at the heart of the Service Agent pillar — 12 teams and growing, building every capability that makes Fin work. You'll partner at the strategic pillar level: broad context across work streams, deep technical understanding of how Fin operates end-to-end, and the autonomy to decide where you need to go next. When we need a new work stream spun up from scratch — a brand new team, an ambiguous problem space, aggressive timelines — you're the person who makes that happen.

The competitive landscape is intense. Fast-moving AI-native startups are coming hard for this space, shipping aggressively and going after the same deals we are. We need someone who thrives under that pressure, who can maintain technical excellence while moving at startup speed within a company that has the resources and customer base to make that speed count.

What will you do?

• Partner at the strategic pillar level. You'll have broad context across work streams and use that to inform technical strategy and investment priorities. What should we care about? Where should we invest? Where do you need to step in? These are your decisions.
• Spin up 0-to-1 work streams. Bring together engineers who've never worked as a team, disambiguate the problem space, build momentum under aggressive timelines, set high expectations, and drive execution.
• Execute on the most ambiguous, highest-stakes problems. You're hands-on. You write code, you ship features, you're deep in the weeds. We've seen too many Principal Engineers who are brilliant but too far from execution to be effective here.
• Lead experimental work at the AI frontier. Run your own A/B tests, do prompt engineering, build evals, and calibrate accuracy, cost, and latency for LLM-powered features. Much of what we're building are new paradigms for customer-facing software.
• Shape long-term technical strategy through execution. Your hands-on work informs the architecture. You're simultaneously building and thinking about what needs to change about how we build products — data models, system design, the shift from GUI-first to agent-first interfaces.
• Work across the full stack in an AI-first development environment. Every engineer has Claude Code with unlimited tokens and a sophisticated ecosystem of MCP servers, skills, and shared context. You'll push the boundaries of what's possible with AI-assisted development and help shape how the entire engineering org works.
• Raise the bar for the people around you. Give direct, actionable feedback that changes outcomes. We don't need someone who mentors juniors on the basics — we need someone who can accelerate and grow the senior and staff engineers around them.

What are we looking for?

The core requirement: engineering depth and product thinking. We need someone who combines deep engineering ability with strong product and design instincts — not one or the other. We don't want engineers who are technically brilliant but disconnected from the product. And we don't want product-minded engineers who have great instincts but can't execute at the level this work demands. You need to be able to both build complex systems AND identify the right problems to solve. This is the single most important dimension we evaluate on.

Beyond that:

• Operated at real scale and has builder energy. You've likely spent time at companies operating at significant scale — the kind of environment where you've seen what large-scale distributed systems actually look like in production. But you also have startup DNA: urgency, resourcefulness, a bias toward building over discussing.
• AI fluency. You're actively experimenting with AI-assisted development, pushing the boundaries of what's possible, and forming opinions about how it changes the way teams build software. This matters more than any specific stack experience.
• Deep technical depth with breadth. You can go deep into the weeds on at least one technical domain, but you also navigate complex multi-team systems with ease. In conversation, you move fluidly from business context to technical strategy to implementation details.
• Communication as a superpower. You can explain to leadership why a technical investment matters, align multiple teams around a complex project, and then walk an engineer through the gnarly implementation details. This role lives and dies on your ability to communicate across every level.
• Extreme autonomy. You partner with the Engineering Director on where you think the pillar needs to go next. You identify problems, form convictions, and act on them. If you're the kind of engineer who waits to be told what to work on, this isn't the right role.
• Critical thinking about the business. You understand what Fin is optimizing for and translate that into technical decisions. Which work streams need investment? Where are we falling behind? What should we defund to go harder somewhere else? You think at this level naturally.
• At least ~10+ years of experience, with significant time as a technical leader driving complex projects across multiple teams and stakeholders.
• Stack agnostic. We use Ruby on Rails, React (migrating from Ember), and AWS. But AI tools increasingly abstract the stack — what matters is your ability to learn, build, and operate effectively with tools like Claude Code. If you're great with a high-level programming language and fluent with AI-assisted development, you'll be productive fast.

Why Fin, why now?

Fin is #1 — and the race is heating up. We built the leading AI agent for customer service, but fast-moving AI-native startups are coming for this space. This is one of the most consequential competitive moments in tech history, and the engineering decisions made in the next 12 months will determine who wins.

A rare pivot that actually worked. Fin has been building for 15 years — deep product, massive customer base, strong revenue. But unlike most legacy SaaS companies, we made a successful pivot to AI. While most of SaaS trends down, Fin trends up. We recently raised $250M to go even further even faster..

AI-first engineering culture. Every engineer gets Claude Code with unlimited Opus 4.6 tokens and 1M context. We're investing heavily in the platform capabilities — MCP servers, skills, shared tooling — that make AI-assisted development genuinely transformative. You'll be at the sharp edge of figuring out what this means for how teams work.

The sweet spot. Big enough to have real resources, customers, and revenue. Small enough that you have genuine agency. Bold enough to make decisions that most companies of this size wouldn't. You come to Fin if you want the impact of a startup with the backing of a company that's been winning for 15 years.

Benefits

We are a well treated bunch, with awesome benefits! If there’s something important to you that’s not on this list, talk to us! 

• Competitive salary, annual bonus and equity
• Regular compensation reviews - we reward great work!
• Generous paid time off above statutory minimum
• Hybrid working
• MacBooks are our standard, but we also offer Windows for certain roles when needed.
• Fun events for employees, friends and family!

#LI-Hybrid