Cashi is Walmart Mexico’s digital wallet app, enabling users to make bill payments, mobile top-ups, and receive cashback across Walmart-affiliated stores. With nearly 6 million users and plans to expand into broader banking services, the product team saw the need for a strategic visual and functional overhaul. I joined the team as a Product Designer to help lead this transformation—particularly focusing on bill payments and the design system efforts that would scale future features.

The existing bill payments experience had usability issues that led to frequent user frustration. Users had to manually enter contract numbers every time they made a payment, even if they had already paid the same bill in the past. The system didn’t prioritize recurring behavior or show saved information clearly, and key UI elements were hidden behind hard-to-notice buttons and bottom sheets.

At the same time, the app’s previous UI lacked consistency. Multiple one-off components were used across screens, and heavy visual elements created performance issues on devices with limited capabilities — particularly important given that over 90% of the user base were on Android, often with older or lower-end hardware.

Bill Payments Redesign

• Created a list-view pattern to surface the user’s most frequent or recent bill numbers/contracts.
• Replaced hidden bottom sheets with clearly visible, tappable items that improved discoverability.
• Leveraged usage patterns to pre-select the most likely payment the user wanted to make — reducing the process from ~6 steps to just 2–3 in most cases.

Design System Overhaul

• Worked closely with developers, PMs, and researchers to define and build a scalable system.
• Focused on lightweight, Android-optimized components for better performance and smoother rendering.
• Delivered token-based specs and component-level prototypes to ensure efficient handoff and implementation.
• Structured documentation included: Component behavior and variants, color, typography, spacing tokens, input constraints and responsive behaviors

Conversion funnel increased by 23%

• From 62% to 85% completion rate within the first two months after implementation.

Interaction time reduced by 50%

• Users could now complete a transaction in as little as 2 steps, thanks to smart defaults and visible saved info.

Better performance on budget devices

• The lightweight UI performed consistently across Android phones dating back to 2019.

Stronger consistency across the app

• The unified design system helped eliminate fragmentation and established clearer UX patterns across features.

While my main focus was on UI design and implementation, this project allowed me to grow significantly in cross-functional collaboration:

• Strengthened my technical communication with developers through structured documentation and working sessions.
• Learned how thoughtful design documentation could save time and reduce ambiguity in handoff stages.
• Delivered high-fidelity component prototypes to clarify interactions and set clear expectations for product behavior.

We were able to deliver a fully functional and scalable design system, along with major improvements in usability for one of the app’s core vertical. This case helped me understand how design decisions directly impact performance, adoption, and trust, especially when dealing with a high-volume, budget-conscious user base.