UX & product certifications
- Nielsen Norman Group UX Certified (UXC #1045574)
- Professional Scrum Master I
- Certified Scrum Product Owner (Scrum Alliance)
- Member, Project Management Institute (PMI)
Researcher, information architect, designer, product owner, manager — 18+ years turning complex digital products into experiences people trust.

Founder, UXellence · UX Design Leader
Matthaios Mantzios is a UX leader who has spent nearly two decades building human-centred digital products in fast-paced, engineering-led environments.
He has led UX teams, owned products used by millions, and guided organizations through change — pairing strategic direction with hands-on craft. As a Scrum Product Owner, he became known for translating complex technical detail into clear business terms and building consensus among senior stakeholders and executive leadership.
That range — researcher, architect, designer, product owner, manager — is what UXellence brings to every engagement: one senior partner who connects research, strategy, design and delivery into a single, accountable thread. For larger programs, Matthaios draws on a trusted network of specialists, staying hands-on as the lead throughout.
Built a remote-first UX/UI practice from the ground up, raising UX maturity across an engineering-led organization and serving institutions including the University of Cambridge Judge Business School, Cambridge University Press and the European Environment Agency.
Owned the vision for a telecom's authentication and profiling platform serving 5M+ user accounts and daily logins — the backbone of an ecosystem of sites and apps.
Led UX designers and researchers, developed research-based UX strategies, and drove a group-wide digital brand merge recognized as a Deutsche Telekom group case study — lifting web-touchpoint satisfaction to an all-time-high 94%.
Delivered self-service and billing products with measurable impact: 90% payment satisfaction, 40% fewer overdue payments, 95% e-billing satisfaction — grounded in PMI-based planning.
Beyond client work, Matthaios is an active voice in the UX community.
He writes about the evolving UX landscape — from AI's impact on design to inclusive UX strategy — for outlets including UX Planet, Fast Company and The Decision Lab, and publishes regularly on Medium.
He is the author of Web and Mobile Accessibility: A Comprehensive Guide to WCAG 2.2, the ADA, and the European Accessibility Act (Second Edition) — a practical guide to WCAG 2.2, the ADA, Section 508 and the European Accessibility Act, available on Amazon — and mentors emerging designers on ADPList.
Whether you need a fresh perspective, a research partner or senior design leadership, UXellence is ready to help.
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