I build software that takes the user’s side.
In browsers, that meant ad blockers, shopping tools, and other browser extensions used by over twenty million people worldwide. With AI agents, it means integrations and harnesses that keep the human in charge.
I’m Zack Babtkis. I was a Senior Staff engineer at PayPal and a founding engineer at ZeroClick, and I now consult independently.
01 — Who you're hiring
Zack Babtkis
You work with me directly: I take the intro call, write the code, and deliver the work.
I’ve also designed, built, and shipped two products alone: TrueRate, a Chrome extension that exposed hidden hotel fees on the major booking sites, and Unhabit, an iOS Safari extension that blocks distracting websites. Together they reached tens of thousands of installs.
LinkedIn · GitHub · the longer story · references on request
02 — Services
What I'm hired for
Agentic AI
MCP server development
Your customers are asking for a Claude or ChatGPT integration. I built agent-facing APIs at ZeroClick. I’ll build your MCP server and submit it to the Claude and ChatGPT directories.
MCP readiness audit · $2,000AI enablement for teams
Your team has the AI tools and little shipped to show for it. At ZeroClick I shipped a product where AI agents wrote the whole codebase. I’ll set your team up to work that way.
Agent-readiness audit · $3,000Prototype to production
You vibe-coded something that works in a demo. I make it survive real users: tests, auth, data, deployment.
Production readiness audit · $2,500Web extensions
Safari & iOS porting
Your extension doesn’t exist on Safari or iPhone. I built Honey’s first iOS extension and owned Pie’s. I’ll port yours and get it through App Store review.
Port assessment · $2,500New extension from scratch
Chrome, Safari, or Firefox. I shipped extension features to twenty million users at Honey and Pie, and built TrueRate alone.
Scoped per projectExtension for your existing app
Your app, extended into Safari. I shipped Unhabit’s iOS Safari extension end to end and built Pie’s app shells.
Scoped per projectApps
Web apps
I’ve built web apps since 2012: seismic dashboards at UC Santa Barbara, the DSP dashboard that won a 2015 UX Award at Gimbal, financing tools at ProducePay, and pie.yt at ZeroClick.
Scoped per projectiOS & Mac apps
Swift shells, Xcode Cloud, and App Store review. I shipped Pie’s iOS and Mac app shells and two products of my own.
Scoped per project03 — Track record
Where I've shipped
PayPal Honey
Senior Staff engineer · designed and built its first iOS browser extension · $4B exit to PayPal20M+ users
Pie Adblock
Founding engineer · owned the Safari and iOS extensions, led the Creator Network2M+ users · 4.9★
pie.yt
Built and shipped it solo. AI agents I directed wrote the entire codebase.Live · try it
ZeroClick
Founding engineer. Built the agent-facing APIs and MCP servers for its agent-commerce infrastructure.2024–2026
Gimbal (Infillion)
Built the DSP dashboard that won a 2015 UX Award and the dashboard merchants used to manage in-store beacons. Worked on mapping human networks (friends, family, shared audiences) from beacon and geofence signals in a graph database.Location intelligence · 4 years
ProducePay
Helped build the trading platform, including the messaging system growers and distributors use to negotiate trades. Led architecture for the Pre-Season financing platform.Produce marketplace · 2018–2019
TrueRate
Chrome extension that revealed hidden hotel fees (resort, wifi, parking) on Expedia, Hotels.com, Travelocity, and Orbitz, with a scraping API and an iOS app behind itBuilt solo · 2019–2020
Unhabit
iOS Safari extension that blocks distracting sites with cooldowns and scheduling, all on-deviceiOS App Store · 2023Earlier: the NEES@UCSB real-time seismic data portal at UC Santa Barbara’s Earth Research Institute.
Working on something like this?
Tell me what you're building and what's in your way. I read every message myself. If I'm not the right person for the job, I'll tell you, and I'll suggest someone who is.