Principal Full Stack AI Engineer

Validity•Boston, MA

26d•$200,000 - $220,000•Hybrid

About The Position

We're building the next generation of email marketing tools at Validity. AI is central to how we build – we develop with agents daily – and to what we build, shipping AI-powered features that help our customers succeed. We're looking for a Principal Full Stack AI Engineer who ships fast, designs systems that last, and holds a high-quality bar across a team that builds with AI every day. We move fast, communicate directly, and debate ideas openly. The best idea wins regardless of who it comes from. We bias toward action – ship, learn, iterate.

Requirements

10+ years of engineering experience shipping impactful products
Deep full-stack experience with React, Next.js, TypeScript, and PostgreSQL
2+ years building agentic AI systems
Demonstrated ability to work across multiple projects simultaneously, leveraging agents to multiply output
Strong code review skills with the judgment to maintain high quality in an AI-assisted development environment
Strong product sense – you understand the product and what users want
Excellent systems design – you architect for clarity, maintainability, and scale
Bias toward action and rapid decision-making
A doer – hands-on with code and experiments daily
A quality gate – you care about getting it right, and you know AI-generated code needs sharp review
Fast and intelligent – you learn fast, make smart decisions quickly, and iterate
An AI-native builder – agentic tools are part of how you work, not an afterthought
Experimentation-obsessed – you validate through building
Comfortable with ambiguity – you forge ahead when the path isn't clear
Collaborative – you thrive on code review and learning from others
Hard-working and motivated – you put in the effort and take pride in what you ship

Nice To Haves

History of 0-to-1 projects

Responsibilities

Quickly build and ship full-stack features
Design and deploy agentic AI systems that solve real user problems
Work across multiple projects simultaneously, using agents to maintain velocity and context across concurrent workstreams
Perform rigorous code review – especially of AI-generated code – ensuring production-grade quality, security, and systems design
Set technical direction through architecture decisions, prototypes, and rapid experimentation
Help define and improve evaluation for agent-powered features
Move from idea to production-ready implementation at speed
Work closely with product managers, shipping, learning, and iterating