Guillaume Caillet — 7+ years of experience — Based in France
My journey into design started way before any formal training — back when I was a kid playing Counter-Strike on the family computer, I wasn't just into the game; I was fascinated by the branding around pro teams like SK, NiP, Fnatic, and VeryGames. I started creating logos and nicknames for my teammates using Photoshop 7 (yes, I was only 6). That's where the story began.
Over time, I grew more curious about how visual systems work and how beautiful things are built. After a (brief and not-so-passionate) detour through an accounting degree, I realigned myself with what had been driving me for years and pursued studies in Design and Engineering.
Today, I'm a Senior Product Designer with 7+ years of experience across industrial, agency, and SaaS environments — from Airbus to PrestaShop, via BeApp and La Capsule.
I specialize in Design Systems, Design Ops, and setting up user research operations that empower teams to make better decisions. My approach combines craft, structure, and collaboration — always with a focus on scaling design sustainably.
My goal is simple: to help teams build consistent, scalable, user-centered products — and to make design a core driver of product performance and team alignment.
Oplit is an Industry 4.0 scale-up helping transform industrial planning and scheduling through product design.
Structuring and evolving the Design System to ensure consistency, scalability, and cross-team adoption. Designing experiences that make industrial complexity simple, intuitive, and efficient. Strengthening collaboration between Design, Product, Tech, and Operations to accelerate decision-making and innovation.
Impact: Improved product scalability, better leverage of user insights, and direct contribution to Oplit's growth in the Industry 4.0 market.
Sr Product Designer & Design System Lead (2024)
Progressively structures and deploys the research system across PrestaShop. Responsible for structuring and making the tools, templates, and user data operationally available so product teams can access them quickly and efficiently. The aim is to provide efficient access to user search when designing PrestaShop products for our 300k+ merchants.
Also working on structuring the Design System to make it robust, flexible and scalable. Proposing areas for development, structuring the team around the project and giving visibility to what we're doing.
Design System contributor (2023)
Involved in structuring and implementing the PrestaShop Design System. Working on the monitoring, implementation, and use of components and design tokens by everyone who uses the design system, as well as the components designed by the Product Designers.
Product Designer (2022)
Within the Customer Platform team, working on the design and improvement of the user experience through the user account and, more generally, the login experience.
In charge of UX at Beapp, working mainly with the UI designer and in contact with all the people involved in the various customer projects (PO, Business, Tech).
Designing experiences for different types of clients in the healthcare, automotive, food, institutional, and other sectors. Running creativity, immersion, and co-creation workshops. In charge of user research and testing.
Work as a UX consultant for companies looking to improve their user experience.
Joined the team of UX/UI designers (UXiD) as part of a process to digitalize the Airbus Group. The team designs and redesigns processes as well as business applications and HMIs, putting people back at the heart of their design.
Responsible for disseminating UX guidelines and best practices throughout the group. Collecting user requirements, participating in the design of business applications, organising information architecture, and working in collaboration with IT and other departments.
Working as a UX designer in section 574 (innovation) at the SNCF in Nantes. In charge of designing personas, user paths, and screen ergonomics for different applications.
An apprentice for 2 years and trained as a web designer with a specialization in UX design, working on several projects and building up solid experience in a field I'm passionate about.
Teaching the basics of UI Design to young designers.
Helping designers, no matter their seniority, to grow and giving them feedbacks about their projects or career perspectives.
Master 2 — UX Design
Bachelor — Design (L3)
Web-Concepteur
I have written a few articles on various subjects, such as design, design systems, and user research.
Guillaume CAILLET on Medium →Design System, Product Design, Research, UI & UX Design
Product Design, Prototypage, Research, UI Design
Product Design, Prototypage, Research, UI Design
Product Design, Prototypage, Research, UI Design
Mobile, Prototypage, Research, UI & UX Design
MaaS, Mobile, Product Design, Prototypage, UI & UX Design
Design System, Product Design, SaaS, UI & UX Design
UI Design, UX Design
Serious Game, UI Design
Structuring and development of the PrestaShop Design System. Provide product and core teams with access to a system that enables them to design coherent, fluid and easily structured experiences.
When I joined in June 2022, the PrestaShop "design system" was a set of advanced UI kits in Figma, not shared as a true library. Product designers worked with their own components, tech teams used a separate framework, and interface consistency was weak.
With multiple touchpoints (main product, help center, marketplace, academy), alignment was critical to scaling both product and brand.
Unification and redesign of the PrestaShop user account, previously split into three separate accounts (Back Office, Marketplace, Business Care).
PrestaShop users struggled to manage their interactions due to three separate accounts: Back Office for shop management, Marketplace account for module purchases, and User account for business care subscription invoices.
These fragmented systems created confusion, inconsistency, and inefficiency. Basic actions like updating emails or passwords required users to contact technical support, leading to unnecessary delays.
Redesign of the account creation and connection flow to make it fluid and simple throughout the PrestaShop product.
PrestaShop users faced multiple points of authentication (product, marketplace, help center, back office), with no consistent flows or shared data. The lack of synchronization between databases resulted in duplicate accounts and authentication failures.
Until recently, there were 2 connection modes (SSO & Connection by ID). The objective was twofold: increase SSO registrations & connections, and make users understand they only need one PrestaShop account.
Redesign of the association flow between the user account and the shop, making it transparent and error-resistant.
The shop association process, particularly for open-source installations, was a major source of confusion. Merchants didn't understand why association was required and abandoned the process — especially when errors occurred.
The association exists because most users have Open Source shops installed locally on their hosting, not always identified as belonging to the owner account. Association creates this connection.