Context
O2's mobile checkout had an abandonment rate well above industry average. Analytics showed users were dropping off at step 2 of 5 — before they'd even entered payment details. The form was technically correct but cognitively overwhelming.
Research
We ran five rounds of usability testing with 6 participants each. Key findings:
- Users couldn't tell how many steps remained
- The "personal data" form had 14 fields visible at once
- Error states appeared only after form submission
- Trust signals (security badges, cancellation policy) were buried below the fold
Design Decisions
Progressive disclosure: Grouped 14 fields into 3 logical steps with clear progress indication. Each step shows only what's needed for that decision.
Inline validation: Real-time feedback on field blur, not on submit. Format hints shown before errors occur.
Trust layer: Security badge, easy cancellation highlight, and customer rating moved to a persistent sidebar — always visible without scrolling.
Mobile-first: Redesigned for thumb reach zones, large touch targets, and keyboard behavior. Desktop adapted from mobile, not the other way around.
Results
- 23% reduction in checkout abandonment
- Average completion time down from 4:20 to 2:55
- Support tickets about checkout errors reduced by 41%
- NPS for the checkout flow: +18 points post-launch