Mexx UX Redesign
Mexx is Argentina's largest tech retailer with 34 years of history. This case study documents how I identified, validated, and redesigned two critical flows — cross-device cart persistence and hidden shipping costs — using user research and real data validation.
This case study is the final project of the UX/UI Design Diploma at Coderhouse, for the Advanced UX/UI Design course.
UX/UI Designer
4 weeks
Solo Project
Context
Mexx leads Argentina's tech retail market but its digital platform had two critical frictions costing real conversions: 80% of users research on mobile but buy on desktop (cart lost between devices), and 100% of surveyed users cited unexpected shipping costs on digital products as a reason for abandonment.
The Problem
Users added products on mobile, then found an empty cart on desktop — up to 15 minutes of rework per session. Digital products like Windows 11 licenses were incorrectly charged physical shipping ($250+), revealed only at the Mercado Pago checkout step, causing immediate abandonment.
Design Process
I applied James Garrett's Five Planes methodology, working from abstract strategy down to concrete visual surface.
Strategy
I conducted a heuristic audit against Nielsen's 10 principles (7 of 10 failed), a strategic survey with 10 users (12 unbiased questions), and analyzed 6 UX laws being violated. I created 2 personas (Lucas, 26, developer; Sofía, 32, freelancer) and journey maps tracing pain points with emotional curves.
Scope
Validated both hypotheses with real data: 80% of users lost carts between devices, 100% cited hidden costs as an abandonment reason. Ran Tree Testing on UXTweak with 10 participants — discovered 'Software' category had only 40% directness, leading to a rename to 'Licencias Digitales'. Mapped 2 core taskflows and redesigned the information architecture.
Structure
Used Lean UX Canvas + FVD Matrix to prioritize 10 ideas. Selected 6 solutions: persistent cart (DB sync instead of localStorage), transparent floating cost breakdown, digital product label, express login modal, guest checkout, and magic link cart recovery. Discarded 4 low-value ideas: WhatsApp cart integration, AFIP tax calculator, AI chatbot, and gamification.
Skeleton
Built a high-fidelity interactive prototype in Figma covering both complete flows. Designed a full design system: Mexx red (#E73E3E) color palette, Inter + Merriweather typography, 4px spacing system, atomic reusable components, and 6 documented UI animations (hero slider, auth modal, cost breakdown, save indicator, loading states, checkout transitions).
Surface
Usability testing on Maze with 10 participants across 2 tasks. Task 1 (cart continuity): 100% success rate, 32s avg time, 80% directness, 0% drop-off. Task 2 (cost transparency): 85.7% success, 71s avg, 40% directness, 14.3% drop-off (rational decision after reviewing cost — not friction). Key insight: 49-51% misclick rate reveals a header hierarchy improvement opportunity.
Results and KPIs
Both hypotheses validated with real data. Cart persistence achieved perfect task completion; transparent cost breakdown eliminated surprise abandonments. The design system is scalable, documented with CSS tokens, and ready for developer handoff.
Learnings
Rigorous research (Nielsen audit + UX Laws + Survey + Tree Testing) identifies real problems — not assumptions. Validation with real users confirms solutions work before implementation. Every design decision in this project was backed by evidence: the FVD matrix rejected 4 ideas, the tree test renamed a category, and Maze testing confirmed both flows were intuitive.