T-Mobile · Design SystemsiOSWeb

FUSE — T-Mobile's UI Component Ecosystem

FUSE is the internal front-end framework and component library behind T-Mobile's retail and internal apps. It had aged off brand, and I had three months to rebuild it, half the time the work was scoped for.

At a glance
My role
UX Designer
Timeline
3 months
Platform
iOS · Web
Scope
120+ components

A system that had drifted

FUSE powers the front end of T-Mobile's retail and internal applications, one shared framework and component library that teams across the org build on. By the time I joined, the components no longer matched the brand, and the iOS patterns didn't follow Apple's HIG. The whole org was also moving from UXPin to Figma, and FUSE had to be migrated before the UXPin license expired.

The old components couldn't be ported as they were. Rebuilding them meant fixing them properly.

The rebuilt FUSE component library: on-brand, WCAG AA, and HIG-aligned.

Tokens through patterns: one shared system top to bottom.

Cut first, then rebuild

The first step was an audit. The migration was the right time to remove what wasn't working, so about a quarter of the library went: anything outdated, redundant, or that wouldn't pass an accessibility check. Teams had to move anyway, so each removed component had a direct replacement and a cutover date.

Then I rebuilt what was left. Every component went into Figma by hand, with tokens, responsive variants, and accessibility checked against Apple's own components. For iOS, I worked with our engineers to move iOS onto SwiftUI. A few patterns needed to be rebuilt from scratch against HIG.

Apple's iOS UI Kit: the reference for every rebuilt component.

The hard parts

Challenge
The migration was scoped at six months. Leadership wanted it in three.
How I handled it
Components got ranked by actual usage, with a workback schedule built around that. Stakeholders saw it early. Cutting a quarter of the library first is what made three months realistic.
Challenge
The old system was the web library reskinned for mobile. Carousels, tooltips, accordions, none of it was built for a phone.
How I handled it
I rebuilt the mobile patterns natively against HIG instead of adapting web components to fit.
Challenge
The components were too rigid to adjust, so developers built their own versions. The same element ended up with several slightly different copies.
How I handled it
I built components teams could adapt themselves, within a structure that kept them consistent.

Buttons

Component spec covering usage, sizing, states, and best practices.

150+ people, one library

FUSE was fully on Figma before the org's enterprise UXPin license ran out. 150+ designers and developers moved to one library that was on brand, built to WCAG AA, and aligned to HIG. Consolidating the legacy systems into one architecture is projected to save around $6.5M a year.

$0M
Est. annual capacity savings
WCAG AA
Accessibility
0+
Designers & developers

$6.5M reflects the savings from consolidating T-Mobile's legacy systems into the unified FUSE architecture, a team-wide outcome my rebuild contributed to.

Next project
Project Leo — Consumer App