Freelancer profile translated to English.
Back to original languageAbout Julien
Solutions Architectand **MongoDB Expert**, I help companies build, repair, and scale their distributed architectures.
My approach is pragmatic: no armchair theory, but solutions proven in the field for demanding environments (Retail, Scale-up, High Traffic).
🧠 My Philosophy:
- Wisdom Driven Engineering: I advocate for a common-sense technical approach.
- Simple > Complex: The best architecture is the one your team can maintain at 3 AM.
- Business First: Every infrastructure choice must serve a concrete business objective.
🎯 My Areas of Expertise:
- Audit & Performance: Diagnosis of your clusters, query optimization, and security (Crisis Management & Deep-Dive).
- Design & Architecture: Design of resilient systems, technology choices, and migration strategies (Legacy to Modern).
- Training & Mentoring: Knowledge transfer to empower your teams on their stacks.
Next expert MongoDB training June 2026 - Ask for the program
🚀 Community Engagement: Leader of the MongoDB User Group (MUG) Lille.
Connecting tech professionals in the North through concrete experience sharing.
📞 Production issue or need for skill enhancement? Let's discuss your stack and your challenges.
🕵️ Entrepreneur: I am also co-founder of The Bounty Hunt. An offbeat (phygital) team-building activity designed to break the ice and reconnect your collaborators during your seminars. Visit thebountyhunt.com for more info!
French
Native or bilingual
English
Fluent
Can work on-site
Lille (up to 50km), Paris (up to 50km)
Experience
- DECATHLONSolutions ArchitectNovember 2024 - Today (1 year and 9 months)Solution Architect - Pricing ProductChallenge: Lead the global redesign of the pricing engine to support the growth and complexity of modern retail.Critical Migration: Design and manage the migration from PostgreSQL to MongoDB to handle the flexibility of pricing schemas across 50+ countries, breaking down into a modular monolith.Architecture Design: Write ADRs (Architecture Decision Records) and design data schemas optimized for scale.Migration Plan: "Zero Downtime" cutover strategy for a system accessed 10M+ times daily by 50+ consumers (Strangler Fig).Product Vision: Align the technical roadmap with business objectives (dynamic pricing, omnichannel).
- DECATHLONTechnical Leader BackendJanuary 2023 - Today (3 years and 7 months)Technical Leader for Decathlon's international Pricing product.Challenge: Ensure the stability and performance of a core business product at the heart of the Decathlon ecosystem. System processing 300M prices and 10M daily calls.Distributed Ecosystem: Orchestration of flows via 300+ Kafka topics feeding 50+ consuming applications.Leadership & Coaching: Recruitment, management, and skill development of a team of developers on performance and resilience challenges.
- Leroy MerlinTechnical Leader Backend - Multi BUsRETAIL (LARGE RETAILERS)June 2021 - January 2023 (1 year and 7 months)Lille, FranceContinuation of the previous mission. Building a new event-driven, multi-BU product co-created with Italy, based on a MongoDB / Google Pub Sub architecture. Generating over 150 million offers daily. Analysis and tuning of MongoDB, FinOps, workload optimization, Terraform automation, admin front-end in Vuejs.Project deployment as a scalable, multi-BU product.Management and mentoring of Italian, Portuguese, and Spanish teams in project onboarding.
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Education
- Engineering DegreeISEN LILLE2013
- TOEICISEN LILLE2013Score : 855