A mobile app designed to assist security guards in verifying purchase slips and detecting unpaid items at retail store exits.
The Challenge
Homecenter Sodimac, a Colombian retail chain, faced challenges with receipt validation and theft detection as guards struggled to spot reused receipts and stolen items, causing delays and errors.
The Solution
We created a flexible flow where receipts are scanned to prevent reuse, and high-risk items are cross-checked against them. Haptic feedback gave real-time alerts, keeping guards focused off-screen.
The Impact
This solution has been implemented and is currently in use across all Homecenter stores in Colombia, improving operational efficiency and security nationwide. As of 2021, Homecenter operates 40 stores across 24 cities and municipalities in Colombia.
I led the UX side of the process, working closely with a UI designer to shape the product from early research through handoff.
Planned and conducted the user research
Facilitated a prioritization workshop to define MVP features
Defined user flows and created wireframes
Conducted user testing and iterated based on findings
Conducted design QA reviews to ensure alignment with approved designs
Sodimac is a leading retail chain in Latin America, specializing in home improvement and construction products. Operating as Homecenter in Colombia, it serves both homeowners and professionals, with a strong presence in 7 countries, over 100 stores, and more than 13,000 employees.
We conducted user and field research, and mapped the security guards' journey to gain a deeper understanding of their receipt validation process, identifying pain points and opportunities for improvement based on their needs.
Field Research: Guards validating purchase slips and monitoring product exits at the store.
User Journey Map: Process security guards follow to validate purchase slips and control product exits. (Visual in Spanish)
Guards Prioritize High-Risk Items for Faster Checks
Trained to recognize high-value and frequently stolen products, they focus on these during verification to speed up the process.
Speed Over Accuracy During Peak Hours
When the store is busy, guards prioritize key purchase details—total amount and item prices—for a quick mental check rather than a full verification.
Multitasking Leads to Verification Errors
Guards handle slip validation, theft monitoring, customer observation, and radio communication, increasing error risks during manual verification.
We translated user insights into design requirements and functionalities, collaborating with the client to prioritize those that delivered the most value for users and the business, ensuring an efficient MVP launch. The focus was on:
Implementing an efficient, structured validation process
Using color coding and interactive feedback (vibration, sound) to highlight issues
Displaying only essential information for quick decision-making
Prioritization Matrix
Categorizing features based on priority for the MVP: must-have, should-have, and nice-to-have. (Visual in Spanish)
Categorizing features based on user needs throughout the app workflow. (Visual in Spanish)
We designed a user flow that leverages guards’ training, allowing them to focus on high-risk items without slowing down operations. At the same time providing flexibility for busy hours, as guards can choose to verify only slips, skipping products, when necessary.
Step 1 - Scan Purchase Slip
Guards scan the purchase slip
The app verifies the slip’s date and code
If invalid, the app provides color-coded feedback
Step 2- Product Verification
Guards scan high-risk items to confirm if they were purchased
The app checks agains scanned receipt
If the product wasn’t paid for, an alert is triggered
User flow: Navigation flow security guards follow to validate purchase slips and control product exits. (Visual in Spanish)
To ensure usability, we tested wireframes using a paper prototype with guards. Key findings included:
Haptic Feedback is Essential
Reduces reliance on reading and allows guards to stay alert.
Displaying product prices aids validation
Enables quick mental calculations for further validation.
An onboarding walkthrough is necessary
Helps new guards quickly understand the tool.
Low-fidelity designs were created to validate the initial flow and were later used to build a paper prototype for user testing. (Visual in Spanish)
The UI designs were developed based on feedback from paper prototype sessions with guards and refined through additional client validations. Once approved, they were handed off to the development team for implementation, with design QAs conducted until launch.
Physical and digital interactions must work together. Haptics, sound, and color were crucial in reducing cognitive load
User testing validated assumptions and informed critical design decisions, making the app truly user-centered