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Independent software engineer · Benfeld, Alsace · Strasbourg - Sélestat axis

A senior .NET engineer in your team, and AI on your data, on your premises.

15 years of software engineering, five of them at Euro-Information (Crédit Mutuel group) on payment regulation. I reinforce .NET and Next.js teams, take over existing applications, and install a RAG or a business assistant inside your own infrastructure - without your data leaving it. On site across Alsace, remote across France and Europe.

Talk about an assignmentSee the career

Reply within one business day, with my real availability

What do you need?

One more senior in your .NET or Next.js team

Context
Understaffed team, committed roadmap, existing codebase
I join
Your team, your rituals, your repository - no imposed method
Stack
.NET 10 / C#, ASP.NET Core, EF Core, Blazor · React 19, Next.js 16, TypeScript
Format
Contract work, on site in Alsace or remote · one daily rate, shared in my first reply
Lead time
Reply within one business day, with my real availability and notice period
Reference
Hager Group (via Soluxan): marking server for extrusion lines, .NET 10 / Blazor / SignalR / SAP, since April 2025
Discuss a contract

Plot 01 - a reinforcement joins the team's rails

Rate
One daily rate for everyone, in my first reply with my availability
Travel
No travel fees from Strasbourg to Sélestat
Reply
Within one business day, from the engineer himself
Code and data
Yours, in your repository, from the first commit
Set-up
Direct, through a consultancy or a freelance platform

You talk directly to the person who will do the work. No sales rep, no discovery call.

01 — Offers and assignments

Three ways of working together, at the same rate

Team reinforcement for IT departments, AI integrated on the data of SMEs and mid-caps, on-site presence in Alsace. Contract work in all three cases, invoiced by the day.

01 — Contracting

.NET contracting and team reinforcement

IT departments, product teams, industrial mid-caps, scale-ups

  • Legacy take-over and modernisation: .NET Framework to .NET 10, WinForms to web, banking technical debt
  • .NET 10 / C# back-ends, ASP.NET Core, EF Core, Blazor and SignalR; React 19 and Next.js 16 front-ends
  • Automated tests, continuous integration, Azure DevOps pipelines - I led that topic at Euro-Information
  • Regulated sectors: PSD2 payments, card acquiring, cryptography, real-time industrial software with SAP
  • .NET 10 LTS
  • C# 14
  • Blazor / SignalR
  • Next.js 16
  • React 19
  • PostgreSQL

Daily-rate contract work, one rate shared in my first reply, monthly invoicing on days worked. Direct or through a consultancy.

Expertise in detail

02 — AI

AI on your data, on your premises

SMEs and mid-caps with an existing IT system that do not know where to start

  • A first use case proven on your documents - most non-adopters say they cannot identify a relevant use case (Bpifrance, January 2026)
  • RAG with the source cited in every answer (Postgres + pgvector), document extraction in a container on your server
  • Business assistant connected to your ERP or document system through MCP; Mistral models (Apache 2.0) hosted in the EU or on your machines
  • All in .NET, every step versioned, tested and replayable - no no-code platform
  • MCP
  • C# MCP SDK
  • Microsoft.Extensions.AI
  • Mistral (Apache 2.0)
  • vLLM · llama.cpp
  • pgvector

Daily rate, contract work or a short scoped assignment. Where the data goes and what it costs: stated before signing.

How I integrate an LLM

03 — On site

On site, along the Strasbourg - Sélestat axis

Companies in southern Bas-Rhin and the Strasbourg area that want someone in their offices

  • Based in Benfeld: Erstein and Sélestat 15 minutes away, Obernai 20, Strasbourg 25 by motorway or train
  • Meeting in your offices the next day, regular on-site presence for scoping and key milestones
  • Travel included in the rate, same daily rate as in Strasbourg
  • The local fabric: Hager Group (Obernai), Socomec (Benfeld), Würth France (Erstein), Euro-Information (Strasbourg)
  • Benfeld
  • Erstein
  • Sélestat
  • Obernai
  • Strasbourg

On site or remote, following your rituals. Full professional English for international contexts.

Coverage area (in French)

02 — Trust and rigour

Fifteen years in two sectors that do not forgive approximation

Payment banking and industry. Every figure below is dated and can be checked on the career page or on LinkedIn.

  1. 2025 – now

    Independent · Hager Group via Soluxan

    Marking server for extrusion lines

  2. 2022 – 2025

    Euro-Information

    Project lead · 2M-customer migration, cryptography

  3. 2019 – 2022

    Euro-Information Développement

    Analyst developer · PSD2 payments, Monetico

  4. 2017 – 2019

    EFOR · assignment at Euro-Information Telecom (NRJ Mobile)

    .NET analyst developer, billing

  5. 2015 – 2017

    GE Power

    Engineering apprentice · UTBM degree 2017

  6. 2014 – 2015

    Alstom Power

    Engineering apprentice

  7. 2009 – 2014

    First software, two-year computing degree

    Studies · Belfort-Montbéliard

15 years
of .NET software engineering, since 2009
first software written in 2009, as a student, then as an apprentice and under contract
5 years
at Euro-Information, Crédit Mutuel group
December 2019 to March 2025, PSD2 payment regulation and Monetico
2M
customers migrated onto Bouygues Telecom's systems
migration batches designed during the takeover of the telecom business, 2022-2025
UTBM
engineering degree, earned through apprenticeship
information systems engineering degree, apprenticeship at Alstom then GE, 2014-2017
From the day he joined the team, Cédric showed an exceptional capacity for work. He got up to speed fast and became autonomous on his own subjects. A real bloodhound: he finds sound solutions to complex problems. He became an important member of the team in very little time, and he shares what he knows with his colleagues with ease.
Paul Avart, project manager and direct manager at Euro-Information - LinkedIn recommendation, 2019, translated from French
Cédric Santiago

Cédric Santiago

Independent software engineer, Benfeld, France. UTBM engineering degree, formerly Euro-Information.

What you keep: the code, the repository and the secrets from the first commit, the documentation, and the access handed back at the end of the assignment.

Hosting and operations, when you have none: Sanfytech, the studio I co-founded in Strasbourg, on OVHcloud servers in France. What is not covered: neither SecNumCloud nor health-data hosting certification. If your project requires either, hosting goes to a qualified operator, named before signing.

03 — Demonstration

A RAG that never leaves your premises

What a document assistant installed on your own server produces: an answer, its sources, and no outbound call.

document-assistant · your server

question

› What is the contractual warranty period on the extrusion range for customer BX-2041?

search · 3 passages retrieved (pgvector, HNSW)

  • contracts/BX-2041/T&C-2025.pdf§ 7.2 Warranty
  • contracts/BX-2041/amendment-03.pdfart. 2
  • quality/after-sales-extrusion.docx§ 4

answer

24 months from commissioning, extended to 36 months by amendment no. 3 of 12/03/2025 for marking heads. Consumables are excluded (after-sales procedure § 4).

sources: T&C-2025 § 7.2 · amendment-03 art. 2 · after-sales § 4

1.9 s · 0 outbound call

  • model: Ministral 3 14B (Apache 2.0)
  • hosting: your server, Alsace
  • outbound traffic: none

The model weights and the vector index stay on your machines. Every answer cites the document and the paragraph it comes from.

Integration in .NET 10 LTS, supported until November 2028, with the C# MCP SDK and Microsoft.Extensions.AI. Mistral models under the Apache 2.0 licence: self-hostable, with no per-token royalty.

The French data protection authority writes that, for personal data or sensitive documentation used in a RAG, an on-premise solution is “more advisable and more secure”, and that RAG “offers better traceability” (questions and answers of 18 July 2024).

How I integrate an LLM into a .NET application

Three levels of sovereignty, one documented choice before signing

Where your data goes depending on the technical choice
API outside the EUEuropean APISelf-hosted
Where the data goesAt the vendor, stored in the United States (e.g. Anthropic)At a European vendor, in the EU (e.g. Mistral)On your servers or at Sanfytech (OVHcloud, France): it never leaves
CostPer token, in dollarsPer token, in euros: the cheapest option under a few tens of millions of tokens per monthA dedicated GPU, roughly €600 to €1,400 (excl. VAT) per month depending on load
What it enablesThe most powerful modelsOpen, competitive models, European data-processing agreementSensitive documents, internal RAG, no outbound call, full traceability
When I recommend itNever for personal data or confidential documentsFor most SME use casesWhen the regulator advises it: personal data or sensitive documentation

04 — Where I work

Based in Benfeld, twenty minutes from the Strasbourg area

On site across Alsace, remote across France and Europe, in the CET timezone. Full professional English for international teams and rituals.

Travel is included in the rate along the Strasbourg - Erstein - Benfeld - Obernai - Sélestat axis. Beyond it, remote by default, with on-site presence for scoping and key milestones - agreed before the assignment starts, not invoiced afterwards.

Coverage area from BenfeldStrasbourg 25 minutes, Erstein 10, Sélestat 15 via the A35 motorway; Obernai 20 minutes via the D426.Strasbourg25 minErstein10 minBenfeldbaseSélestat15 minObernai20 minA35D426
Strasbourg 25 minutes, Erstein 10, Sélestat 15 via the A35 motorway; Obernai 20 minutes via the D426.

05 — Contact

A role to fill, an application to take over, a use case to prove?

Tell me the context, the stack and the duration. I reply with my real availability and my notice period - or with a straight no if I cannot take it on.

Describe your need07 45 28 82 10

Reply within one business day, with my real availability