Available from September 7 · Freelance / Contract

Baptiste Lejeune
Senior .NET Developer

Microservices & event-driven architecture · 10 years · mission-critical systems

10 years of C# / .NET development, from full stack to mission-critical systems. In recent years, focused on microservices with Clean Architecture and event-driven architecture (Kafka), notably in financial environments.

exp 10 years stack C# · .NET 6/8 · Kafka · Azure base Le Creusot (France) remote yes + on-site

Technical Expertise

The foundation of a backend profile geared toward distributed architecture.

Languages & Frameworks

C# / .NET 6/8expert
ASP.NET Coreexpert
.NET Framework 4.8advanced
T-SQLadvanced
JavaScript / jQueryintermediate

Architecture & Messaging

Clean Architectureexpert
Microservicesexpert
Apache Kafkaadvanced
API REST / CQRSadvanced
Event-Drivenadvanced

Data

SQL Serverexpert
MongoDBadvanced
PostgreSQL / Redisadvanced
Snowflakeintermediate
Entity Frameworkadvanced

Cloud & DevOps

Docker / Kubernetesadvanced
Azure Pipelinesadvanced
OpenShiftadvanced
CI/CDadvanced
AWS S3intermediate

Quality & Testing

xUnit / Moqexpert
SpecFlow (BDD)advanced
Test Containersadvanced
SonarQubeadvanced
FluentAssertionsadvanced

Security & Observability

Keycloak / OAuth2advanced
OpenTelemetryadvanced
Grafana / dashboardsadvanced
Polly (resilience)advanced
Log4netadvanced

Recent Experience

Large-account, mission-critical and regulated environments.

● 2025 — present

.NET Developer — Finance Marketplace

Peaksys · client Cdiscount (Casino Group)

.NET 6/8 microservices in Clean Architecture managing the financial lifecycle of sellers: commission calculation and reimbursement, financial entries, multi-currency support, multi-country regulatory compliance.

KafkaMongoDBSnowflakeKubernetesOpenTelemetryGrafanaKeycloak

2023 — 2025

.NET Developer — Ticketless Entry

APRR (Eiffage Group)

High-availability services handling up to 150,000 transactions/hour with sub-2-second responses. REST API and asynchronous communication via Kafka, containerization on OpenShift.

.NET 8KafkaPostgreSQLOpenShiftTest Containers

2022 — 2023

.NET Developer — Legal Document Generation

Septeo Solutions Notaires

Secure legal document generation features, legal compliance, resolution of production performance issues.

.NET Framework 4.8SQL ServerAzure DevOps

2016 — 2022

Full Stack then Lead Developer — Mission-critical ERP

Neos-SDI · client Stokomani

Operational maintenance of a production ERP (orders, inventory, suppliers), technical team leadership, code review, production T-SQL quick fixes.

C#T-SQLSSIS / SSRSEntity Framework

Eager to Master

Solid in backend .NET, curious and eager to level up on other stacks.

My core expertise is backend .NET, but I readily integrate into a project's stack — whether technologies I've already touched and want to deepen, or new ones to discover. Here's what I'm eager to master: a great way to add value while growing my skills.

Angular

To explore

Encountered from afar (mostly AngularJS, the older version); keen to train seriously on a full stack project.

Blazor

Familiar ground

Razor syntax I know from MVC (@Html, server-side views) — a natural bridge to the front end while staying in the .NET ecosystem.

Vue.js

To explore

New to me, but the component approach appeals to me; keen to learn it on a real project.

Next.js / React

To explore

An ecosystem I want to discover; my JS foundation and experience with component architectures make it easy to pick up.

AI / LLM in apps

To explore

Integrating LLMs and AI into business applications: a topic that strongly motivates me and that I already use via Claude Code / Copilot.

App Insights

Touched on

Used for performance monitoring and real-time error management (ERP project); eager to leverage it more deeply, building on my observability experience.

Node.js · PHP · Umbraco

Touched on

Encountered across projects (including an Umbraco 7→10 migration); foundations in place, ready to level up if a project calls for it.

Protobuf · Material Design

Touched on

Used on a test simulator (APRR): Protobuf serialization for inter-service messaging, Material Design for the UI. Keen to practice them further.

Also practiced (legacy): VB.NET, WPF / XAML / MVVM, SSIS / SSRS, KnockoutJS, Infragistics, UWP — technologies encountered on earlier projects, available if a mission requires them.

Geographic Range

Full remote, or on-site missions across a wide central-eastern radius.

Based in Le Creusot (Saône-et-Loire, France), I work fully remote or hybrid. Key asset: the Le Creusot TGV station opens up the entire Paris–Lyon axis with direct access, making many on-site missions perfectly viable.

🚄 Le Creusot–Montceau–Montchanin TGV station — Paris in 1h17 direct · Lyon in ~40 min direct · trains until evening (≈9:47 PM). Allow ~15 min from Le Creusot to reach the station (Montchanin).

Daily commute — no conditions

≤ 45 min each way — daily on-site presence possible

Chalon-sur-Saône

car → ~40 min

TER → ~40 min

road / TER

500 € / day · negotiable

Beaune

TER → ~45 min

car → ~1h

TER / road

510 € / day · negotiable

Daily commute — if ≥ 2 remote days

≤ 1h30 each way — daily viable with at least 2 remote days / week

Lyon

Le Creusot → ~40 min

TGV direct

+ ~15 min to station (Montchanin)

Round trip same day

out · morning → Lyon in ~40 min

back · until 10:23 PM last departure

520 € / day · negotiable

Mâcon

car → ~1h

road / TGV

510 € / day · negotiable

Dijon

car → ~1h15

TER → ~1h · via Beaune

road / TER

520 € / day · negotiable

Moulins

car → ~1h15

road

520 € / day · negotiable

Bourg-en-Bresse

car → ~1h30

road

530 € / day · negotiable

Weekly on-site base

1h30 to 3h each way — weekday presence, weekly round trip (arrive Sunday evening, return on last on-site day)

Paris

Le Creusot → 1h17

TGV direct · 5–6/day

+ ~15 min to station (Montchanin)

Comfortable weekly

out · from 6:53 AM → Paris 8:14 AM

back · until 9:47 PM, arrival ~10:20 PM

640 € / day · negotiable

🛏 apart-hotel near mission ~1000–1400 €/month

Besançon

car → ~2h

road

550 € / day · negotiable

🛏 apart-hotel / residence ~700–950 €/month

Saint-Étienne

Le Creusot → ~1h40

TGV via Lyon

+ ~15 min to station (Montchanin)

560 € / day · negotiable

🛏 apart-hotel / residence ~650–900 €/month

Clermont-Ferrand

car → ~2h15

road

560 € / day · negotiable

🛏 apart-hotel / residence ~700–950 €/month

Grenoble

car → ~2h45

road

570 € / day · negotiable

🛏 apart-hotel / residence ~750–1000 €/month

Valence

car → ~2h15

road

580 € / day · negotiable

🛏 apart-hotel / residence ~700–950 €/month

Genève / Annecy

car → ~2h45

road

640 € / day · negotiable

🛏 apart-hotel / residence ~950–1300 €/month

Nearby cities, normally daily commute (2 remote days) — but also workable on a weekly on-site base if the mission needs more presence, by taking local lodging. Accommodation counted Sunday evening to Thursday evening (≈ 4 nights/week).

Lyon

Le Creusot → ~40 min

TGV direct

+ ~15 min to station (Montchanin)

560 € / day · negotiable · lodging included

🛏 apart-hotel / residence ~700–950 €/month (Sun→Thu)

Dijon

car → ~1h15

TER → ~1h · via Beaune

road / TER

550 € / day · negotiable · lodging included

🛏 apart-hotel / residence ~550–750 €/month (Sun→Thu)

Mâcon

car → ~1h

road / TGV

540 € / day · negotiable · lodging included

🛏 apart-hotel / residence ~480–680 €/month (Sun→Thu)

Moulins

car → ~1h15

road

550 € / day · negotiable · lodging included

🛏 apart-hotel / residence ~450–650 €/month (Sun→Thu)

Bourg-en-Bresse

car → ~1h30

road

560 € / day · negotiable · lodging included

🛏 apart-hotel / residence ~500–700 €/month (Sun→Thu)

Every other week on-site

3h–4h each way — alternating on-site presence, remote on the off week

Avignon / Aix

via Lyon → ~3h

TGV + transfer

+ ~15 min to station (Montchanin)

1 week in 2 on-site

out · Sun. evening, transfer Lyon

back · last on-site day, evening

600 € / day · negotiable

🛏 apart-hotel / residence ~400–550 €/month (1 wk in 2)

Marseille

via Lyon → ~3h30

TGV + transfer

+ ~15 min to station (Montchanin)

620 € / day · negotiable

🛏 apart-hotel / residence ~400–600 €/month (1 wk in 2)

Montpellier

via Lyon → ~3h30

TGV + transfer

+ ~15 min to station (Montchanin)

620 € / day · negotiable

🛏 apart-hotel / residence ~400–550 €/month (1 wk in 2)

Travel arrangement. For on-site missions between 1h30 and 3h each way, I work on a weekly basis: arrive Sunday evening, return on the evening of the last on-site day. Beyond 3h, I favor an every-other-week presence with remote work on the intervening week. Late TGV schedules (departures until ~9:47 PM, station open in the evening) make these rhythms reliable year-round toward Paris and Lyon. The TER Mobigo network also serves Dijon, Beaune and Chalon alongside the TGV. Times are indicative — to be confirmed on SNCF Connect depending on the day.

Total travel time. The durations shown are door-to-door estimates. The trip between the arrival station and the mission site (by transit) adds to the total: if this addition exceeds a category's ceiling, the city moves to the next category. Beyond 4h total, the mission isn't retained. A mission site close to the station is therefore a real plus.

Day rate. Rates indicated for a long mission, negotiable depending on duration, context and technical scope. Fully remote: €500 / day. On-site rates include travel and accommodation in an apart-hotel / lease-free residence (flexible booking, no application file or deposit, services included). For every-other-week presence, accommodation is only booked on the on-site weeks (monthly cost reduced accordingly). Open to umbrella-company arrangements.

Terms & Preferences

What makes a collaboration run smoothly on both sides.

Status

Freelance

Open to umbrella-company arrangements

Availability

From Sept. 7, 2026

Long missions welcome

Focus areas

Microservices · Full stack

Modern .NET, event-driven, finance

Work mode

Remote or hybrid

On-site possible (see range)

Methodology

Agile / SCRUM

TDD / BDD, code review

Languages

FR native · EN B2

Comfortable with technical discussions in English

A technically demanding mission?

Let's talk. I respond quickly and can share my availability and references.

baplej@gmail.com +33 6 47 23 27 55 in/baplej