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Julien SacréJS

Julien Sacré

Android Developer

€650/day
Paris, FR
8-15 years

Average response time: 1 hour

Freelancer profile translated to English.
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About Julien

Senior Android Developer with 14 years of experience, specializing in technically demanding mobile applications: fintech, banking, payment on Android terminals.

Autonomous and proactive, I bring real added value to technical decisions and architecture, without needing supervision. I quickly onboard existing projects or start from scratch, with a clear vision of current Android best practices.

I maintain a constant watch on the Android ecosystem and agentic AI, following developments in real-time and applying them concretely in my projects.

What I master: Kotlin, Jetpack Compose, Material 3, MVVM/MVI, Coroutines/Flow, Hilt, Retrofit, Room, Firebase. For cross-platform projects: Kotlin Multiplatform and Compose Multiplatform (Android part only from a shared base).

Field References: ING, Banque des Territoires, Direct Assurance, CAWL (Worldline × Crédit Agricole joint-venture), up2pay/LCL, Smile&Pay, Accor ALL, Canal+. Nepting SDK integration on Android payment terminals, CI/CD pipelines Fastlane + Bitbucket Pipelines.

In parallel, I develop my own applications: NomadBudget (nomadic budget, KMP, RevenueCat), Factura (invoices for artisans, offline-first) and Guadeloupe Local (UGC community app).

I use agentic AI daily in my workflow: Claude Code, MCP, n8n, to automate repetitive tasks and speed up processes. I also build my own tools: custom skills and a long-term memory system for AI agents.

Full remote only. Digital nomad for several years, I work on French business hours.
  • French

    Native or bilingual

  • English

    Conversational

Remote only
Primarily works remotely

Experience

  • Gobeyond Studio (Groupe Concentrix) — ex-Webhelp, ex-MyStudioFactory
    Android Developer
    BANKING AND INSURANCE
    May 2021 - Today (5 years and 1 month)
    Paris, France
    Active project:
    - Banque des Territoires: banking application
    - Direct Assurance: insurance application
    - CAWL: payment on Android terminals (Nepting SDK), Worldline × Crédit Agricole joint-venture launched in 2024
    - Up2pay / Caisse Digital / Monem (LCL): Crédit Agricole payment suite on Android terminals, shared codebase (Nepting SDK)
    - Knave: white-label car rental (Volvo, Chatenet, Cavallari...)

    Delivered projects:
    - ING: banking application
    - Smile&Pay: payment on Android terminals (Nepting SDK)

    Technical achievements:
    - Refactoring / modernizing legacy: RxJava → Coroutines/Flow, XML → Compose, Java → Kotlin, Groovy → Kotlin DSL, MVP → MVVM
    - Implementation of CI/CD pipelines with Fastlane and Bitbucket Pipelines
    - Integration of proprietary SDKs (Nepting, banking and auth SDKs), POS hardware management (Ingenico, PAX)

    Stack: Kotlin, Jetpack Compose, Material 3, MVVM, Coroutines, Flow, Hilt, Firebase, Retrofit, Fastlane, Bitbucket Pipelines
    Kotlin Jetpack Compose Material UI Coroutines Fastlane
  • Extia
    Consulting Engineer — Android Development
    ENTERTAINMENT AND LEISURE
    April 2019 - May 2021 (2 years and 1 month)
    Île-de-France, France
    - Accor Mission (Sept. 2020 — May 2021) — maintenance and evolution of the Accor ALL app (several million users)

    - Canal+ Mission (June 2020) — adaptation of MyCANAL as a launcher on TV boxes with TNT tuner, Android TV
    RxJava Java Kotlin Android TV GitHub
  • Nexway
    Android Developer / Backend Java
    RETAIL (LARGE RETAILERS)
    August 2015 - July 2018 (2 years and 11 months)
    Île-de-France, France
    Development and maintenance of Android applications for digital content distribution (white-label app store)
    Backend development: REST APIs and asynchronous microservices with Spring Boot and RabbitMQ
    Setup and maintenance of transactional and marketing email pipelines

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Education

  • Professional Degree Web and Android Development
    INSSET
    2013
    Licence Pro Développement Web et Android

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