UX & product certifications
- Nielsen Norman Group UX Certified (UXC #1045574)
- Professional Scrum Master I
- Certified Scrum Product Owner (Scrum Alliance)
- Member, Project Management Institute
About
A UX leader with 18+ years in research, design, product ownership and management.
Researcher, information architect, designer, product owner and manager, turning complex digital products into experiences people trust.
About Matthaios Mantzios
MM
Matthaios Mantzios
Founder, UXellence · UX Design Leader
Nielsen Norman Group UX CertifiedScrum Product OwnerAuthor
The short version
Nearly two decades across research, design, product and team leadership.
Matthaios Mantzios is a UX leader who has spent nearly two decades building human-centered digital products in engineering-led organizations.
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 runs research, strategy, design and delivery as one piece of work, with one person accountable for it. For larger programs, Matthaios draws on a trusted network of specialists, staying hands-on as the lead throughout. Matthaios Mantzios leads every engagement himself, and we take on a limited number at a time.
Career
A track record across scale and sectors
Head of UX & Design — since 2022
Built a remote-first UX and user interface (UI) practice from the ground up, raising UX maturity across an engineering-led organization and serving major European institutions and academic organizations.
Scrum Product Owner — digital identity
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.
UX Expert, then Digital Interfaces and UX Team Leader
Led UX designers and researchers, developed research-based UX strategies, and drove a group-wide digital brand merge recognized as a case study within the wider group — lifting web-touchpoint satisfaction to an all-time-high 94%.
Project Manager, then Manager, Web Projects
Delivered self-service and billing products with measurable impact: 90% satisfaction with online payment, overdue payments down 40% and a 95% rise in satisfaction with online bills, planned on Project Management Institute (PMI) practice.
Credentials
Certified expertise, formal foundations
Education
- M.Sc. Mechanical Engineering — University of Arizona (Reliability & Quality; fellowship & scholarship)
- Mechanical & Industrial Engineering Diploma — University of Thessaly (5-year program)
Continuous learning
- Multiple Nielsen Norman Group courses: UX & analytics, usability, mobile UX
- Design Thinking for Innovation — University of Virginia
- Front-end & responsive design — University of Michigan
Thought leadership
Sharing what works with the wider field.
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 the Web Content Accessibility Guidelines (WCAG) 2.2, the Americans with Disabilities Act (ADA), Section 508 and the European Accessibility Act (EAA), available on Amazon — and mentors emerging designers on ADPList.
Standards work
Matthaios is Greece's delegated expert in CEN-CENELEC JTC 21 Working Group 4, "Foundational and societal aspects", appointed in September 2026 on the nomination of ELOT, the national standards body. The working group develops the European standards behind the EU AI Act's requirements for logging, transparency, human oversight, accuracy and robustness.
In Greek, he wrote UXellence's free guide to declaring AI systems in the national AI Registry for public-sector bodies.
Featured in & on
- UX Planet
- Fast Company
- The Decision Lab
- Amazon · Author
- ADPList · Mentor
Industries served
- Telecom
- Retail & e-commerce
- Media & TV
- Insurance
- Public sector
- Publishing
- Higher education
For researchers, editors and partners
Publications & citations
Our research publications each have a digital object identifier (DOI) and a license chosen for how they are meant to be used.
| Publication | Identifier | License, and why |
|---|---|---|
| Room to Disagree: a framework for AI oversight interfaces (2026) | DOI 10.5281/zenodo.22079129 | CC BY 4.0: anyone may use and adapt the framework, including commercially. |
| The human in the loop is a job: role profiles for human oversight (2026) | DOI 10.5281/zenodo.23061031 | CC BY 4.0: organizations can turn the profiles into their own job descriptions. |
| Όροι σύμβασης για ανθρώπινη εποπτεία (Greek, 2026) | DOI 10.5281/zenodo.23058907 | CC BY 4.0: procurement teams can paste and adapt the terms in their own contracts. |
| Δήλωση στο Μητρώο Συστημάτων Τεχνητής Νοημοσύνης: οδηγός για φορείς του δημοσίου (Greek, 2026) | DOI 10.5281/zenodo.23018687 | CC BY-NC-ND 4.0: share it freely, but keep the guidance intact and free of charge. |
| Web and Mobile Accessibility, second edition (book) | ISBN 979-8185857137 (hardcover), 979-8296794642 (paperback) | Published book, available from Amazon. |
Researcher identifiers
- ORCID 0009-0002-2659-0910
- Google Scholar profile
- ISNI 0000 0005 3086 9791
- Wikidata Q140757497
Press, talks and partnerships
For interviews, talks, review copies or partnership inquiries, email matthaios@uxellence.gr. Editors will find a short bio on the book page.
Matthaios on LinkedIn and ADPList, where he mentors designers.
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