Benjamin Mayrargue, C# Developer in Colombes, France
Benjamin Mayrargue

C# Developer in Colombes, France

Member since August 9, 2013
Benjamin is a seasoned C# developer, architect, and devops. He designs, creates, and deploys mobile apps, desktop apps, APIs, database, and cloud systems. He is specialized in cross-platform C# core techs on Windows, Mac, and Linux. He has worked for large companies and startups, in small teams, large teams, and alone. He now has a well-organized powerful home office.
Benjamin is now available for hire


  • Freelance
    Xamarin, .NET Core, C++, Android, iOS, Technical Architecture, Training
  • Metageek
    Xamarin C#, Android, iOS, API, USB Accessory, C/C++
  • Airbus Helicopter
    C#, Xamarin, iOS, iPad, Bluetooth



Colombes, France



Preferred Environment

Visual Studio, VS Code, Windows

The most amazing...

...project I've worked on is Wi-Spy Air, the best mobile wifi mapper for planning, validating, and fixing wifi in any company.


  • Developer

    2009 - PRESENT
    • Created Wi-Spy Air iOS/Android apps for a Toptal client. This enterprise-level tool analyzes the wifi low-level protocols for planning of wifi deployment and maintenance. It is connected to a backoffice through an API.
    • Built "Cosmo Moto" iOS and Android apps along with the microservices API server. The app works with a Bluetooth safety light for motocycles. It detects accidents or falls and automatically calls for emergency help and notifies your loved ones.
    • Developed Vfr Tracks iOS/Android apps. Vfr Tracks is a tracker for leisure planes. It can livestream the plane position and flight parameters and browse and display details of publicly-saved tracks and their pictures.
    • Programmed, a defunct NFC tag manager app for Android. The app automates actions based on the scanned wifi tag.
    • Created Radio, apps for iOS and Android, capable of playing most radio streams in the highest quality and using a second volume level slider for fine-tuned volume control for very quiet places, such as in bed.
    • Taught five-day Xamarin seminars in training centers (10 sessions in two years).
    • Created the application, including website, backoffice, and tools. Managed a team of four. I was the CTO of the company.
    • Helped developers in live sessions through ASP.NET Core discovery and real-world usage, OAuth2 real-world usage, code debugging, and other things.
    • Set up a production-grade Kubernetes cluster on bare metal and migrated .NET Core apps, including a Blazor app with a Seq log aggregator and Kibana server. Set up RBAC authentication using Azure AD, Nginx, and Let's Encrypt automatic TLS certificate creation and assignment.
    • Integrated (and migrated) Stripe billing to directly sell my own software components on
    Technologies: Xamarin, .NET Core, C++, Android, iOS, Technical Architecture, Training
  • Expert Mobile Developer

    2018 - 2019
    • Created two Air Viewer apps for iOS and Android, available in the stores.
    Technologies: Xamarin C#, Android, iOS, API, USB Accessory, C/C++
  • Expert

    2018 - 2019
    Airbus Helicopter
    • Added BLE communication protocols to an existing Xamarin Forms app.
    Technologies: C#, Xamarin, iOS, iPad, Bluetooth
  • Expert Mobile Developer

    2017 - 2019
    Cosmo Connected
    • Created both Android and iOS apps, available in the store.
    Technologies: Xamarin, C#, .NET Core, MySQL, Google Cloud, BLE, Real-time Location Tracking
  • R&D Manager

    2008 - 2010
    • Led a research and development team that handled load testing, international billing, real-time web UI, migrations to ASP.NET MVC, and study of micro architecture.
    Technologies: C#, ASP.NET, SQL Server
  • C# Developer

    2002 - 2008
    Telecom Italia
    • Worked on an internal search engine using COM objects.
    • Created a captive web search portal for kids.
    • Created and deployed a transcoding and distribution system of movie files for IPTV.
    Technologies: ASP.NET, SQL Server, JavaScript, HTML, CSS


  • Wi-Spy Air (Development)

    An enterprise-level wifi network analysis tool dedicated to wifi planification and maintenance. It captures low-level wifi packets and frequency using a scanner to create a map of your wifi network, compare it later for maintenance, and detect lots of issues with wifi deployments.

    This app for Android/iOS uses an USB "Wi-Spy Air" device (plugged in the lightning port for iOS) and features real-time update of all fields in all "opened" screens using a reactive software architecture, and correctly manages all the background states of any Android or iOS version.

    The apps are connected to a back end through an API. It features user registration and connection, enterprise level connection, reporting of wifi snapshots, and categorization in sites/rooms (autocompletion fields).

    The USB connection is managed by a C/C++ library.

  • Cosmo Moto (Development)

    Cosmo is the first connected safety brake light for motocycles. I built the whole architecture: Android/iOS apps using Xamarin Native, secure and documented APIs in .NET Core for Linux/Debian on Google Cloud, MySQL schema and queries, and worker microservices plugged into the existing Drupal back end.

    The app communicates with the Cosmo device through Bluetooth LE. It features a strong light, intelligent crash detection, real-time GPS position reporting, fail-safe crash reporting to loved ones and paid assistance. Technically both apps can update the device firmware.

    Both apps also features real-time and offline voice command recognition in five languages using a C++ library. The firmware update stack for the BLE device is written in pure C#.

    The API back end has these microservices: an OAuth2 client, a public API front, a MySQL database, scheduled tasks using Google Cloud PubSub, and a private API. It exchanges data with the eCommerce website.

  • Vfr Tracks (Development)

    These Android and iOS mobile apps, dedicated to leisure aviation, track the position and flight parameters of small aircrafts in real time. The app creates maps of your flights that you can share with your teams or livestream to your followers (like your instructor).

    I created both mobile apps (using Xamarin Native). The apps use an API which supports SignalR for live streams, push notifications, and deep links, and background state management on all devices and OS versions (Android 5.0-10, iOS 10-13).

    It is available in English and French.

    Both apps feature an infinite smooth scrollable "news style" feed using an asynchronous pageable API and a Facebook-style loading state animation.

  • (Development)

    This Android and iOS app configures NFC tags, which are small stickers with a chip, like those used to protect merchandise in clothing stores.

    After configuration, the tags will trigger actions when a phone is in its near field. For complex actions, the app must be installed, but it does not need to be running.

    The app features an easy UI to read and write complex actions to any NFC tag, limited only by the memory available in the tag. It does not need an internet connection to work.

    The NFC stack is written in pure C#.

  • Airbus Helicopter (Development)

    Upgraded a large and technical iPad app written three years ago, dedicated to helicopter pilots, which registers specific flight parameters and is aimed at replacing the manually written flight reports.

    Analyzed the exchanges between the app and the API server, which was a legacy ASP.NET web API, to propose changes and improve performance. Implemented the changes and also upgraded parts of the web API to a new version.

    The app has heavy technical debt, written in an old version of Xamarin Forms. It now uses the latest technologies, has many of its bugs and inconsistent behaviors fixed, and is much quicker to react to user actions.

    I also worked on the DevOps by setting up continuous integration and automatic build in the cloud, and trained an Indian developer in best practices.

    Finally, I designed and implemented Bluetooth LE communication to a private flight device to get more flight data.

  • Shapr Personal Networking (Development)

    I created the first versions of the mobile apps for Android and iOS, and then I implemented the evolutions and other updates for two years. I gave advice on app content and design as well as support on design tools. I recruited, managed, and trained additional external developers to support a fluctuating workload of up to four devs.

    - Full Xamarin C# platform-specific technology.
    - Device-independent vector graphics dramatically reduced the time lost testing and fixing graphics on multiple devices.
    - Used my own component XamSvg available on component stores.
    - Integrated LinkedIn Connect, Facebook Analytics, Google Analytics, and AppsFlyer.

  • XamSvg (Development)

    A vector graphics library for Xamarin iOS, Android, UWP (Windows), and Xamarin Forms.

    The resolution of retina screens was a revolution. With each increase of pixels per inch on mobile phone screens, developers have to create new images for each new resolution, increasing the workload and the application weight.

    SVG vector graphics are very small files describing an image mathematically through lines and curves. They can change their size and resolution without any pixelation. There is no app performance degradation at all, as the device GPU knows how to accelerate these renderings.

    This library allows you to change just one file in order to change your icons. Additionally, the component supports pressed states and color remapping, so one SVG image file is enough.

  • Speaker at Mobile Conference at IBM Headquarters (Other amazing things)

    I spoke at the mobile conference in November, 2013, in Paris, France at IBM headquarters. I demonstrated how to use C# to code an Android app and an iOS app, and how to reduce code duplication up to 80% by using a cross-platform library. I also demonstrated Windows phone apps, a Windows 8 Store app, and a Mac App Store app.

  • Radio (Development)

    Radio is a radio app for Android and iOS.

    It features customizable skins and a brushed UI. It is capable of playing most radio streams in their highest quality and has an exclusive second volume level slider for fine tuning in very quiet places.

    On Android, it uses ExoPlayer. On iOS, it uses the low-level audio subsystem.

  • Vapolia (Development)

    I created this website in 2008 in ASP.NET 4 and jQuery. I used it as a template to check the upgrade paths for these technologies:

    ASP.NET MVC 4 and Aspx (2012)
    ASP.NET MVC 5 and razor (2014)
    ASP.NET Core 1.0 (2016)
    ASP.NET Core 2.0 (2017)
    ASP.NET Core 2.1 (2018)
    ASP.NET Core 2.2 (2019)
    ASP.NET Core 3.0 and Blazor (2019)

    This website is running inside a KVM virtual machine on a dedicated server on a host provider. The virtual orchestrator used is Proxmox on Debian 9. I am the sole manager for the server and its security.

    I have successfully set up and tested a Kubernetes cluster on this machine, and I'm planning to move in the cluster, using a .NET Core Linux image and helm.


  • Languages

    C#, SQL, C#.NET
  • Frameworks

    .NET Core, .NET, JSON Web Tokens (JWT), Razor Pages, Blazor
  • Libraries/APIs

    Xamarin.iOS, Xamarin.Android, Web API, PubSubJS
  • Tools

    Bitbucket, Git, Azure Active Directory B2C (ADB2C), Trello, Slack, WiX Installer, Helm, RabbitMQ
  • Paradigms

    Concurrent Programming, Model View Controller (MVC), Design Patterns, Microservices Architecture
  • Platforms

    Xamarin, Azure, Kubernetes, Amazon Web Services (AWS)
  • Storage

    MySQL, SQL Server DBA, Google Cloud
  • Other

    Crash Fixing, Xamarin Forms, Windows Presentation Foundation (WPF), Internationalization, Cloud Infrastructure, MSMQ


  • Master's degree in Artificial Intelligence
    1995 - 1995
    Jussieu University (Paris VI) - Paris, France
  • Master of Science degree in General Engineering
    1990 - 1995
    Esme Sudria High School - Paris, France


  • ASP.NET Web Developer - Level 3
  • Visual Studio 2019 Expert
  • Querying Data with T-SQL Expert
  • Entity Framework Core Expert
  • C# Expert
  • Planning Microsoft Azure Solutions - Proficient
  • iOS Expert
  • iOS Publishing, Distribution, Deployment Expert
  • Android Expert
  • English Level C1
    JULY 2019 - PRESENT

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