Senior Full-stack AI Engineer

StefanBrain Is Hiring A Senior Full Stack Engineer
Senior Full-Stack AI Engineer

(Full-time | Remote | Salary: Negotiable + Equity)

About StefanBrain

StefanBrain is an agentic platform built to fully solve DTC marketing. The endpoint we are building towards is a fully-autonomous solution where virtually anyone on earth can ask StefanBrain to help their business get customers, and the platform figures out how to reach this goal and then accomplishes it.

Since soft-launching to the public in June, we’ve seen strong growth and have fully validated product-market fit. The platform is already closing in on $1MM in ARR with a 90% retention rate. We’ve accomplished this purely on word-of-mouth, and without a single dollar spent on marketing.

In aggregate, the businesses on StefanBrain spend over $100MM per month on Meta alone and there are 3,558 ad accounts connected to StefanBrain at the time of this Job Description being crafted.

All of this is great, but it’s also just the beginning, and that’s where you come in.

Our founding engineering team is amazing, but also stretched thin. We are about to start a multi-month engagement with an external partner who will be assisting on the data and infra development team which will help, but we still need at least one more full-stack engineer to join us.

About the Role

We're looking for a Senior Full-Stack AI Engineer to help scale StefanBrain into the operating system every serious DTC brand runs on. In this role you’ll be assisting with the revamping of legacy features that need significant upgrades, as well as leading the development of new features. You will also help own platform stability, backend implementations, and interoperability between the various features on our platform.

What You'll Do

Architect and ship full-stack features across the agentic platform — copy generation, creative, CRO, video, Build mode, and media buying tools

Work hands-on with frontier and fine-tuned open-source models across multiple providers. We run a multi-model architecture — different models for chat, tools, and high-volume processing — and we're building toward orchestrated routing where the best model wins each slot. You'd be in the middle of that.

Own features end-to-end: spec → UX → backend → deployment

Help us scale from hundreds of active businesses to thousands without breaking what works — session capacity, Meta integration and the connection funnel, file handling, the unglamorous stuff that decides whether growth compounds or stalls

Ship inside an eval-gated pipeline.

Collaborate directly with our CEO and founding engineering team on product direction and the marketing IP that powers everything

What We're Looking For

A beast at using AI coding tools. Claude Code, Codex, Cursor. You know how to write code but you rarely do it by hand. Instead, you orchestrate.

Real full-stack chops. Front-end UX (React/Next.js) and back-end infra (Node, Python, Postgres, S3, queueing, agent orchestration). You can hold the whole system in your head.

Shipping speed without sloppiness. You know the difference between "move fast and break things" and "move fast and ship things that hold up under 9-figure ad spend." We've learned this one the hard way once or twice, which is exactly why the eval harness exists.

Startup Mentality. We are a startup. We’ve seen fantastic growth already without any heavy promotion. As we ramp up those efforts, the platform is positioned to quickly grow into a 9 - and then 10 figure valuation. But this only happens with a truly dedicated team. Which means this is not a 9-to-5 role. If that's a dealbreaker, no hard feelings but the role is not for you. If building the future of DTC marketing alongside the best operators in the space gets you fired up, let’s talk.

Bonus: agent frameworks, video/image generation pipelines, Meta Ads API, AWS-native data infrastructure (Step Functions, Bedrock, S3 lakehouse), or model evaluation/routing experience.

Intelligence. Not just “I score high on an IQ test.” Are you someone who can think through a problem along multiple dimensions? Are you reactive or proactive? Can you take a step back to look at downstream consequences of any action without getting stuck in a world of hypotheticals?

Strong Communication Skills. Every job description on earth says this, but we really mean it. You need to be able to clearly and effectively communicate with both our team and our customers. As a fast-moving startup, you will sometimes be on the frontlines. So if a feature isn’t working properly, or there’s a bug, or someone simply needs help getting the best results with StefanBrain, you should be prepared to step in and assist.

What You Get

Potential to earn vested equity in StefanBrain after a trial period

Negotiable salary based on experience (we pay top of market for the right person)

Flexible hours and location (we have guys working all night, guys working mornings, people spread across time zones). Willing to relocate to South Florida? Bonus, not a must.

The chance to build tools 9-figure brands rely on every single day — and to watch a feature you shipped Tuesday show up in a customer's ad account Wednesday