I built a React component library that reached 80% adoption across Internet Brands' healthcare application portfolio and cut delivery for a new app from 10 months to 1. It mattered because the same UI was being rebuilt by hand in every project, and that duplication was the difference between a one-month build and a ten-month one. I owned the architecture, the dumb/smart component split it was built on, and the documentation and training that let the team keep contributing to it after I'd moved on.
Walking into a mess
A senior developer had just left, and nobody remaining understood the existing React/Redux applications, so the team of four juniors with no React experience couldn't ship features or fix bugs without a fight. Components were duplicated across applications with no documentation, delivery was running past ten months, and all of it had to stay HIPAA-compliant for the clinical office apps. I started by documenting the existing patterns, finding the duplication, and mapping dependencies across the microservices, which is where the openings for consolidation showed up.
The library
The architecture leaned on a dumb/smart split: presentational components stayed stateless and reusable, and the containers wired them to data and Redux, so the same UI primitives dropped into any app without dragging business logic along. I built the centralized library on modern hooks and Redux patterns, documented every component, and set up the build pipeline and NPM packaging so other teams could install it like any dependency. The healthcare compliance work folded in here too, since the shared patterns were where I enforced the security requirements once instead of per-app.
The library only mattered if the team could own it, so I trained seven developers on React fundamentals and library contribution, ran daily code reviews and pair-programming sessions, and mentored four juniors through their harder projects. I also redesigned the desktop-only messaging app into a mobile-first experience, re-architecting the layout on CSS Grid and Flexbox and shipping it in a month while mentoring a junior through the build.
The results
Before
10 months
After
1 month
Before
0%
After
80%
Before
0
After
30+
Before
0
After
7
Before
—
After
4
What I took from it
A component library scales the team, not just the code; the dumb/smart split is what let four juniors ship confidently against UI they didn't have to understand line by line. The library became the foundation for five-plus healthcare apps, and the developers I trained kept it alive after I left, which is the only real measure of whether a system was worth building.