I design complex products with high standards. currently at Oplit

Guillaume Caillet Senior Product Designer France

Over the last 7 years, I've contributed to the design and improvement of B2B SaaS products — alongside teams at Oplit (industrial schedulers), PrestaShop (300k+ merchants), Airbus and SNCF. I've led design systems, run audits, and shipped infrastructure that compounds across teams.

What I'm looking for: high-stakes products where design co-pilots strategy — not a service function.

Discover my work →

Who am I?

My relationship with design started before any formal training. As a kid, I played FPS games on the family computer, but what fascinated me wasn't the game — it was the branding of pro teams. At 6, I was creating logos for my teammates in Photoshop 7. What took root back then never left me: a curiosity for visual systems, and the drive to build tools as much as to use them.

Today I'm a Senior Product Designer at Oplit, a B2B SaaS platform for industrial scheduling. I design for planners and shop-floor operators in luxury watchmaking, aerospace, and precision engineering — expert users, in contexts where every design decision has real operational impact. My role goes beyond interface design: I took over and deployed Oplit's design system as a structural element of the organization, aligning design, engineering, and product around a shared language. This kind of leverage — turning a design tool into decision infrastructure — is what defines my practice.

What draws me are SaaS environments where design shapes how organizations actually operate — not just how products look. The work that matters isn't screens: it's a decision framework that held, a component system that accelerated the entire team, user research that redirected a roadmap. I'm naturally moving toward roles where I own the product — where design vision and product strategy are one and the same.

Professional Experiences

Sept. 2025 — Present

Senior Product Designer Oplit

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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.

June 2022 — Aug. 2025

Product Designer PrestaShop

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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.

June 2021 — June 2022

UX/UI Designer BeApp

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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.

Oct. 2020 — June 2021

UX Designer Consultant La Capsule

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Work as a UX consultant for companies looking to improve their user experience.

Sept. 2018 — June 2020

UX Designer Airbus Atlantique

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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.

March 2018 — Aug. 2018

UX Designer — Internship SNCF

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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.

Aug. 2015 — Sept. 2017

UX Designer — Work-study StéreoSuper

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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.

Other experiences

2025 — Present

Teacher Ecole de design Nantes Atlantique

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Teaching the basics of UI Design to young designers.

2024 — Present

Mentor ADPList

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Helping designers, no matter their seniority, to grow and giving them feedbacks about their projects or career perspectives.

2021 — Present

Speaker & Jury ECV Nantes

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Design System workshop with M1 UX — building a foundation & understanding the need for a design system (2026)
Jury M2 UX — end-of-study projects (2026)
Eco-design & Design System 2023, 2024, 2025 (Speaker)
Design System '22-'23 (Annual project) — 100% students graduated
User Research Methods '21-'22 (Lecturer)

2025

Lecturer École de Design Nantes

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1st year — Design & UX/UI fundamentals
2nd year — Figma training

2020 — Present

Freelancing

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Studies

2017 — 2020

ECV Nantes

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Master 2 — UX Design
Bachelor — Design (L3)

2015 — 2017

CESI Nantes

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Web-Concepteur

Mentoring

Get mentored by Guillaume CAILLET on ADPList →

Articles

I have written a few articles on various subjects, such as design, design systems, and user research.

Guillaume CAILLET on Medium →

Podcasts

#3 Partager la connaissance de son produit — Guillaume Caillet — PrestaShop → Interview with Simon Robic on mobile-first design →

Templates for Notion

Guillaume Caillet | Notion Template Creator →

Curriculum Vitae

Download CV (PDF) →

Useful links

Email me Connect on LinkedIn

Projects

2026

01

Oplit

Opal DS · Corrective Actions

Design System · Design Ops · Automation

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02

Oplit

Multi-select & Sticky Action Bar

Interaction Design · Pattern Design · Industrial SaaS

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2025

03

Personal

Figma Plugin — Local Components Collector

Design Ops · Tooling · Figma Plugin

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04

Oplit

Opal DS · Audit

Design System · Audit · Design Ops

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05

Oplit

Capacity Transfer Between Sectors

Product Design · Strategy · Sales Enablement

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06

PrestaShop

Design System

Design System · Research · Product Design

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07

PrestaShop

Customer Account

Product Design · Research · UI Design

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2024

08

PrestaShop

Sign in / Sign up Flow

Product Design · Research · UI Design

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09

PrestaShop

Store Association Flow

Product Design · Research · UI Design

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Earlier projects — concept work, prototypes and student projects I still find relevant.

Mon Caviste Mobile · Prototyping · Research · UI & UX Design
TAN MaaS · Mobile · Product Design · Prototyping · UI & UX Design
Dashboard Fournitures Design System · Product Design · SaaS · UI & UX Design
Hip Opsession UI Design · UX Design
UX Cards Serious Game · UI Design

← Back to projects

Case Study PrestaShop

PrestaShop Design System

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.

Design System Product Design Research UI Design UX Design

100% of product squads use the DS in design

80% adoption in tech teams

-50% reduction in development time

PrestaShop Design System — Project cover

Context

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.

Approach

Structured the design system team and implemented shared ownership around a unified workflow.
Set up contribution processes, component review cycles, and regular design-tech alignment meetings.
Built a transparent Kanban in Notion, accessible to both design and tech, to track every component request and status.
Audited the existing system and produced actionable recommendations to realign the system for future growth.
Pushed adoption of documentation standards, making documentation a Go/No-Go criterion for any new component.
Introduced and started implementing design tokens, following best practices for primitive and semantic layers.

Outcome

Implementation of design/tech contribution processes, documentation, comprehensive auditing, governance, and shared Kanban.
Initial implementation of design tokens on test projects (inspired by Nathan Curtis).
Reduction in design/documentation debt, alignment with tech on nomenclature.

What's next

Ongoing documentation standardization across all components.
Rollout of experience libraries for specialized squads, maintaining brand and UX alignment.
Continued monitoring of DS adoption and iteration of governance processes.

← Back to projects

Case Study PrestaShop

PrestaShop Customer Account

Unifying three fragmented PrestaShop accounts (Back Office, Marketplace, Business Care) into one — so users finally stop calling support to update an email.

Product Design Prototyping Research UI Design

3 → 1 accounts unified into a single customer account

0 support requests needed for basic account updates

Kano basic need — structured as infrastructure, not feature

PrestaShop Customer Account — Project cover

Context

Back Office — Employee profile (before)

Marketplace Addons — Account page — Marketplace Addons — Account (before)

Research & Discovery

Decisions & Trade-offs

Collaboration

Design Solution

Unified Account — Final design — Unified Customer Account — Final design

Outcome & Measurement

← Back to projects

Case Study PrestaShop

Sign in / Sign up Flow

Cutting authentication errors in half by redesigning sign-in across the entire PrestaShop ecosystem (back office, marketplace, help center).

Product Design Prototyping Research UI Design

-50% authentication errors (7k avg vs 15k before)

-50% flow length reduction

50% of logins via Google SSO within 6 months

Context

Research & Discovery

Decisions & Trade-offs

Collaboration

Design Solution

Outcome & Measurement

← Back to projects

Case Study PrestaShop

Store Association Flow

Redesign of the association flow between the user account and the shop, making it transparent and error-resistant.

Product Design Prototyping Research UI Design

600+ successful associations per day

~–40% estimated drop in error-driven abandonment

PrestaShop Store Association Flow — Project cover

Context

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.

Approach

Conducted research to identify key pain points and abandonment triggers.
Redesigned the flow to require only the necessary information, providing clear guidance and error correction.
Modeled the new process on the SaaS "Edition" experience, offering seamless association for recognized shop owners.
Prototyped the new flow (including a demonstrative video) and validated improvements with stakeholders.

Store Association — Research and flow mapping — Research — Flow mapping and wireframes

Store Association — Current production flow — Current production flow — Association success path

Store Association — New workflow — New association workflow — Simplified steps

Outcome

Major improvement in user comprehension and reduced frustration.
Most shop traffic now flows through the updated payment platform and onboarding.
Unified the experience with the "Edition" SaaS model for consistency.

← Back to projects

Case Study Oplit · Opal DS

Oplit — Opal DS · Corrective Actions

Executing the design system remediation plan: rebuilding 44 components, applying 2,634 token bindings, and establishing a dev-alignment workflow that accelerates feature delivery by 20–30%.

Design System Design Ops Automation Figma MCP

92 → 2 634 token bindings applied

9% → 100% component compliance rate

44 components rebuilt · 0 hardcoded values

Execution

Before

box-shadow: 0 2px 8px #3f64ff40;
background: #3f64ff;
border: 1px solid #1a1a2e;

→

After

box-shadow: {shadow.button.default};
background: {color.brand.primary.default};
border: 1px solid {color.neutral.900};

Automation

Dev Alignment

🎨

Figma

Design + tokens

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📄

Notion

States, variants, props

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📚

Storybook

Dev review

→

✓

Linear

Ticket closed

Outcome

← Back to projects

Case Study Tooling

Figma Plugin — Local Components Collector

A JavaScript plugin built with the Figma Plugin API to automate local component audits — reducing DS audit time from days to hours.

Tooling JavaScript Figma Plugin API Design Ops

days → hours DS audit time reduction

0 manual file navigation needed

Solo shipped without engineering bandwidth

Problem

Approach

How it works

Local Components Collector ✕

Button/Primary×12HIGH

Card/Item×8HIGH

Icon/Arrow×5MED

Tag/Status×3LOW

Impact

← Back to projects

Case Study Oplit · Opal DS

Oplit — Opal DS · Audit

A systematic Opal DS audit — graded findings against four industry frameworks, with a phased remediation plan I executed over the following months.

Design System Audit Design Ops

3 levels severity grading

3 horizons remediation plan

4 frameworks Atomic Design · BEM · DTCG · WCAG

Context

Methodology

Component	Token usage	Naming	Accessibility	Status
Button	✗	⚠	✓	NON-COMPLIANT
TextField	⚠	✓	⚠	NEEDS WORK
Chip	✓	✓	✓	COMPLIANT
Dialog	✗	✗	⚠	NON-COMPLIANT
Switch	✓	✓	✓	COMPLIANT

Findings

Remediation Plan

← Back to projects

Case Study Oplit

Capacity Transfer Between Sectors

A capacity-transfer feature that lets schedulers reallocate production across workshops in seconds — backed by structured documentation and a demo grounded in a real customer.

Product Design Product Strategy Sales Enablement Documentation

Multi-site shipped in the Stock module · industrial scope

7-step spec FOCUSED docs framework + Linear specs

9+ interviews demo grounded in real customer research

Context

Problem

Approach

Impact

Reflection

← Back to projects

Case Study Oplit

Oplit — Multi-select & Sticky Action Bar

One coupled pattern — multi-select triggers a sticky action bar — so schedulers can update 50 work orders in one click instead of fifty. Same behavior across cards and Gantt views.

Industrial SaaS Interaction Design Pattern Design Component Design

2,250 bulk actions in first 30 days (Mixpanel)

4 views consistent behavior across cards & Gantt

~7 days design / 4 months to production

50-100 min/week saved per planner (estimated)