01
−15 %
Infrastructure spend
30% lower cost per run on the heaviest PostgreSQL queries through query and index tuning.
SFR · Outcomes documented in my CVProfessional profile / Paris, France / Full-Stack & Data
Julien Esnault
Cloud &FinOps.
Engineering with financial discipline.
Cloud architecture, cost optimisation and reliable delivery. Full-Stack and Data Engineering expertise applied to business-critical platforms.
Open to opportunities worldwideCertified expertiseExplore credentials
Solutions ArchitectAssociate · SAA-C03
FinOps CertifiedEngineerFinOps CertifiedFOCUS AnalystARCHITECTURE / OPTIMISATION / DELIVERYThe experience behind the outcomes
01 / Experience & impactCLOUD / DATA / DELIVERY
Professional experience.
Experience across cloud cost management, business-critical software and data infrastructure. Selected outcomes from my work at SFR.
02
−30 %
Post-release defects
99% success on Kafka exchanges and 25% fewer business rejections.
SFR · Outcomes documented in my CV03
÷ 2
Release cycle time
Quality gates, repeatable deployments and a 97% pipeline success rate.
SFR · Outcomes documented in my CVSEP. 2021 — SEP. 2026
Paris, France
SFR
TelecommunicationsLead Full-Stack Developer · Java / React
Technical lead on Gencia, SFR’s business-critical platform orchestrating fibre connection workflows, used daily by field teams and partners. End-to-end ownership from the React front end to Java microservices, Kafka streams and GCP hosting.
Explore this experienceClose experience details at SFR
THE WORK BEHIND THE OUTCOMES
I owned Gencia end to end: React/TypeScript front end, Java Spring Boot microservices, Kafka event-driven flows and GCP hosting. I worked directly with the Product Owner to turn user needs into technical specifications, in an Agile (Scrum, Kanban), product-driven setup with TDD, SOLID principles and hexagonal architecture.
Full-stack development (Java / React)
Built Java Spring Boot microservices and REST APIs documented with OpenAPI, consumed by the React front end and internal partners. Redesigned the UI/UX in React/TypeScript.
40% lower P95 latency on critical screens
Event-driven architecture (Kafka)
Designed asynchronous Apache Kafka flows (producers/consumers, error recovery, deduplication) to make business-critical exchanges reliable.
99% exchange success · 25% fewer business rejections
Quality, testing & architecture
Applied hexagonal architecture (DDD), automated unit, integration and functional tests, and made code reviews systematic.
30% fewer post-release defects
CI/CD & GCP cloud
Built GitHub Actions pipelines with quality gates. Ran Docker workloads on GCP (Cloud Run, Kubernetes), optimising costs and elasticity.
Releases 2x faster · 97% pipeline success · 15% lower infrastructure spend
Data performance (PostgreSQL)
Optimised queries and indexes on the heaviest PostgreSQL workloads.
30% lower cost per run on the heaviest queries
Generative AI & documentation
Integrated generative AI into the development lifecycle (testing, code review, security) and maintained living documentation with MkDocs.
AI-assisted dev workflow · living docs
Stack: Java, Spring Boot, React, TypeScript, Node.js, Apache Kafka, REST APIs, PostgreSQL, Docker, Kubernetes, GCP (Cloud Run), GitHub Actions, Datadog, Terraform, MkDocs. Outcomes documented in my CV.
JAN. — DEC. 2021
Station F, Paris
Unybone
HealthtechFull-Stack & 3D Software Engineer
Early-stage startup specialised in biomechanical analysis through 3D scanning. From scan data to real-time WebGL visualisation: an investor demo delivered in under 8 weeks for a strategic fundraising round.
Explore this experienceClose experience details at Unybone
THE WORK BEHIND THE OUTCOMES
At Station F, I worked with the founders to turn biomechanical scan data into an interactive demonstrator for investor presentations, iterating quickly on product feedback.
Investor prototype & product collaboration
Built the interactive demonstrator used as the main fundraising presentation. Scoped and prioritised investor-ready features with the founders, and packaged reproducible demo scenarios with clear product storytelling.
Investor demonstrator delivered in under 8 weeks
Real-time 3D visualisation
Integrated the biomechanical scan-to-3D rendering pipeline and optimised the WebGL rendering engine for smooth, consistent navigation during demos.
60 FPS in key demo scenarios
Loading & rendering performance
Profiled the application, preloaded key 3D assets and added caching to cut startup time and make the demo feel more responsive.
Startup reduced from 5.5s to 1.9s · 65% faster
Scan data & demo reliability
Implemented scan data ingestion and normalisation with validation and error handling. Added targeted tests and development conventions to reduce crashes and blocking behaviour as the prototype evolved.
98% processing success on test/demo datasets · 99% crash-free internal demo sessions
Results documented in my CV; performance and reliability figures refer to test datasets and demo scenarios.
Connecting the disciplines
Cloud & FinOpsAWS · GCP · FOCUS · allocation & showback
DevOps & IaCTerraform · Kubernetes · Docker · CI/CD
Full-Stack & DataReact · Next.js · Python · SQL · observability
02 / Certifications & learning
Qualifications & credentials.
Professional qualifications in Cloud & FinOps, supported by continued learning in data engineering and artificial intelligence.
CertificationAmazon Web Services
Solutions Architect
Associate · SAA-C03
Issued August 2026Valid until August 2029
CLOUD ARCHITECTURE
CertificationThe Linux Foundation
FinOps Certified
Engineer
Issued March 2025Valid until March 2027
CLOUD FINANCIAL MANAGEMENT
CertificationFinOps Foundation
FinOps Certified
FOCUS Analyst
Issued April 2025Valid until April 2027
COST & USAGE DATA
ID · rv35ipvfangqThe complete picture
LinkedIn profile13 credentials, including the 3 featured certifications above
Claude with Amazon BedrockAnthropic · TrainingMarch 2026
SQL AssociateDataCamp · CertificationFebruary 2026
Issued: February 2026 · Valid until February 2028Credential ID: SQA0015685497356Find this credential on my LinkedIn profile
TOEIC Listening & Reading · 875 / 990ETS · Language testMarch 2026
Issued: March 2026 · Valid until March 2028Find this credential on my LinkedIn profile
Quantitative ResearchJ.P. Morgan · Forage · Job simulationDecember 2025
Machine Learning: Concepts & Practical ProjectsSkills4All · Course completionDecember 2025
Introduction to FOCUSFinOps Foundation · TrainingMarch 2025
Issued: March 2025 · Valid until March 2027Credential ID: 9aoc2sidni6zFind this credential on my LinkedIn profile
Career Essentials in Generative AIMicrosoft · LinkedIn · TrainingFebruary 2025
Issued: February 2025Find this credential on my LinkedIn profile
Front-End Web DevelopmentSkills4All · Course completionFebruary 2025
Generative AI FundamentalsDatabricks · AccreditationDecember 2024
Issued: December 2024 · Valid until December 2026Credential ID: 124917499Find this credential on my LinkedIn profile
Engineering degree — Sup de VinciEmineo Education · Sup de Vinci · DegreeSeptember 2024
Issued: September 2024Find this credential on my LinkedIn profile
Courses, accreditations and job simulations are distinguished from professional certifications.See the work behind the skills
03 / Selected workPLATFORMS & ENGINEERING
Projects & platforms.
A selection of professional work, independent products and technical resources.
8 projects
01SFR · Gencia
Enterprise platform
Business-critical fibre connection workflows. Java microservices, Kafka event streams, React front end and CI/CD on GCP at SFR.
Java · Spring Boot · React · Kafka · GCP · GitHub ActionsProfessional experience02Portfolio Terminal
Portfolio analytics
A multi-asset portfolio platform with AI-assisted imports, risk analysis and performance analytics. Designed and developed end to end.
Next.js · TypeScript · AI / LLM · Finance analyticsVisit platform03GoldenCompass
Financial education
Financial education, budgeting tools and mortgage simulations. A product combining structured content, data and interactive planning tools.
Next.js · Prisma · Data visualisationVisit platform04Databricks
Data analysis
Analysis of global vaccination data using the Databricks ecosystem: data cleaning, transformation and visualisation.
PySpark · Delta Lake · SQL · DatabricksView repository05System Design
Architecture resource
An educational roadmap covering scalability, distributed systems, caching and architecture fundamentals.
Architecture · Distributed systems · Learning resourcesExplore resource06Data Structures
Interactive learning
An interactive resource for learning data structures, algorithms and computational complexity.
Next.js · MDX · AlgorithmsExplore resource07Airneis
E-commerce
A premium furniture e-commerce platform, from catalogue and cart workflows to responsive interfaces and containerised delivery.
Next.js · REST APIs · Docker · GitLabView repository08Biomechanics
Investor prototype
An interactive prototype connecting biomechanical scan data with real-time 3D visualisation, developed at Station F.
3D rendering · Data integration · Product prototypingProfessional experienceIdeas &
Perspectives
Notes on cloud, cost, governance and machine learning, written while building the things they describe.