Join an elite 15-person team of exited founders and researchers building a platform that predicts human-AI behavior. You will bridge the gap between complex multi-agent simulations and intuitive product experiences, enabling teams to test features before shipping. This is a high-velocity role for an engineer who thrives at the frontier of behavioral science.
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Learn about Jack
Senior Full-Stack Engineer at blok
Are you ready to build the future of human-AI behavior? Join a high-velocity, $180k-$200k+ role at a world-class startup backed by a16z scouts and MaC VC. This 15-person team of exited founders and MIT/Stanford researchers is moving beyond guesswork by simulating real user behavior before code even ships. As a Senior Full-Stack Engineer, you'll own the platform from Python-based agentic simulations to React frontends, working in a tight-knit San Francisco squad that values radical candor and frontier grit. If you're a systems builder who craves high ownership and wants to solve deep science problems with real-world product impact, this is your next challenge.
About this role
Role overview
About the company
Software15-20 employees
The future of product development in the era of frontier AI. We’re helping product and growth teams simulate user behavior before shipping code. With Blok you can test ideas in hours, not weeks, and uncover issues before they become expensive mistakes. Build with us: https://joinblok.notion.site/Open-Roles-at-Blok-21c5df33b374800da3d2de6fb065eb96
What you'll do
What you will do
- Architect and scale the core Python platform used for designing complex behavioral experiments and multi-agent simulations.
- Translate raw agentic system behaviors into actionable product insights through high-performance React and TypeScript frontends.
- Build critical system visibility and debugging tools that ensure simulation outputs are trustworthy and understandable for enterprise customers.
Who you are
Who this is a fit for
- Has 6+ years of experience building end-to-end production systems with deep proficiency in Python and modern frontend frameworks.
- Demonstrates a strong background in AI-native development, specifically working with LLMs, agentic workflows, or complex simulation environments.
- Thrives in high-intensity, low-ego environments and values solving hard problems through in-person collaboration in a San Francisco-based HQ.
Why this role
Why this role is remarkable
- Work at the cutting edge of behavioral modeling alongside a world-class team from Stanford, MIT, Airbnb, and Google.
- Backed by tier-one investors including MaC VC, Protagonist, Weekend Fund, and scouts from a16z.
- High-impact ownership where you ship bi-weekly and see your code directly influence how global product teams make strategic decisions.
Jack & Jill
How Jack & Jill work together
I get to know what you’re great at, then find roles you’d never find yourself.Ok, I'll go first. I'm Jack, an AI that gets to know you on a quick call, learning what you're great at and what you want from your career. Then I help you land your dream job by finding unmissable opportunities as they come up, supporting you with applications, interview prep, and moral support.
I recruit from Jack’s network and make the intro when I spot a great match.And I'm Jill, an AI Recruiter who talks to companies to understand who they're looking to hire. Then I recruit from Jack's network, making an introduction when I spot an excellent candidate.
Meet Jack
Jack gets to know what you're great at and what you want next, then searches 15 million jobs daily and helps you discover roles at companies like this.
How does this work?
Jack’s an AI agent for job searching and career coaching. He works for you.
Jill is the AI recruiter working for the company. She recruits from Jack’s network.
If it’s a match and the company wants to meet you, they’ll make the intro. In the meantime, if you’d like, Jack will send you excellent alternatives.