Brian MacDonald
Founder & Lead Engineer · @BmacBuilds
I'm an engineer and an operator. I've spent 20 years building businesses and running marketing across the tech industry — the last few architecting AI systems that let companies scale without adding headcount. Now I build all of it in public as @BmacBuilds.
I grew up in Northern California in a family rooted in technology. I spent 8 years at American Express, built and exited an e-commerce business in my twenties, played professional beach volleyball, and ran marketing operations and lead-gen for dozens of companies in the years that followed. The thread never changed: build things that work, and build the marketing engine that grows them.
Somewhere in those years I noticed what the desk does. It builds the business and quietly takes the body — mine included. It also taught me the hard truth about most founder-led companies: the founder isn't running a business, they're running a very demanding job. If you can't leave for a morning without the revenue noticing, you don't own the machine. You are the machine.
So today I build machines. Mavrick is an AI coworker I built end to end, from the infrastructure up — starting as an AI receptionist that answers every new lead in under 60 seconds, qualifies, books, and follows up, natively in Slack, connected to the 3,200+ tools a modern team already uses. Around it I run a Claude Code command-and-control hierarchy: AI agents that execute the marketing operation on rails, with human approval on anything that spends money or talks to a customer. That's the freedom stack. It's why I can be in the water on a Tuesday morning and on top of the numbers by nine.
Building in public means showing the calls, not just the credits. A few of the decisions behind Mavrick:
- Predictable AI cost. I put a hard spend cap and model-tiering on the whole system — the cheap model does the routine work, the expensive one only when it earns it. AI bills don't get to surprise you.
- It asks before it acts. Anything that spends money or sends a message waits for a human's yes. The agent can never quietly do something you didn't approve.
- It can't double-act. Built so a hiccup can't make it run the same job twice — the unglamorous engineering that keeps an autonomous system trustworthy.
- Compliant by construction. Cold outreach follows the rules in code, not in a policy doc someone forgets.
- Pointed at the money. The hard part isn't automating everything — it's knowing which work quietly costs you revenue and putting AI exactly there.
- Shipped, not slideware. It's live in production — Slack-native, free to start, SOC 2 underway.
Mavrick is the proof point for everything I believe about AI in a business: pointed at the money, integrated with the tools the team already uses, and engineered to last. The wedge is deliberate — Mavrick starts as your AI receptionist and setter, earns trust on the phones, and levels up toward the thing I'm actually building: the world's best AI sales agent.
Based in Orange County, California.