Senior C# Developer

Engineering & Development
|
Senior
Senior
Colombia
Brazil
|
Colombia
Brazil
open
July 31, 2025

About the company

First Line Software works with some of the worlds top businesses and organisations in industries like healthcare, real estate, data engineering, warehouse automation, retail digitalisation, mobile app development, and e-commerce. Our projects are as varied as our people, and our people are as talented as they come.

We prefer working as a transparent and supportive team, who shares our knowledge as well as our success.

Lets see what we can create together!

‍

The project and your role

We are seeking a passionate Senior C# Developer to join our team and contribute to a long-running, high-impact software product for the real estate industry. This core product, built on ASP.NET and SQL Server with a multi-tenant architecture, has over 20 years of production use and is undergoing significant modernization, including the introduction of Git, CI/CD, and database migrations. You will maintain the current system while driving its evolution towards modern engineering standards, working closely with architecture and product teams.

Key Responsibilities

  • Maintain and enhance the legacy ASP.NET application with a focus on stability and careful evolution.
  • Propose and implement modernization efforts across source control, deployment processes, and database practices.
  • Create and maintain database migration scripts.
  • Help establish and optimize Development, Staging, and Test environments.
  • Collaborate with cross-functional teams to analyze and solve complex production issues.
  • Document and refactor legacy code for improved clarity and maintainability.
  • Contribute to the introduction and enforcement of development standards and guidelines.
  • Participate actively in code reviews and mentor other team members on best practices.
  • Take ownership of technical decisions, articulate your reasoning clearly, and advocate effectively for improvements.
  • Proactively identify technical debt and suggest pragmatic paths forward for resolution.

‍

Your skills

  • Strong proficiency in C# and ASP.NET Web Forms/MVC, with significant experience in legacy systems.
  • Expertise in SQL Server, including complex stored procedures and functions.
  • Proficient with Git (basic to intermediate level).
  • Demonstrated ability to maintain, debug, and improve older .NET codebases.
  • Proactive, self-driven, and analytical, comfortable with ownership and advocating for technical improvements.
  • Strong communication and collaboration skills across cross-functional teams.
  • Eager to learn and drive legacy systems toward modern engineering standards.


    • Nice to have:

  • Experience with Flyway or other database migration tools.
  • Familiarity with DevOps pipelines (e.g., Azure DevOps, GitHub Actions).
  • Exposure to Modern .NET (.NET 6+).
  • Basic understanding of HTML/CSS/JavaScript for frontend troubleshooting.
  • Experience working with multi-tenant architectures.

    • ‍

    What we can offer

    The FLS difference

    • Our modern stack projects are the right mix of exciting and challenging
    • Gain access to our diverse range of training programs, courses, and certifications;
    • Choose your work style - remote, on-site or hybrid in one of our stunning offices. We offer the freedom of flexible working hours.
    • Enhance your language skills with our corporate English classes
    • Work from anywhere and explore the world with our Workation program

    ‍

    Start Application

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    Our Hiring Process

    Getting started with us

    Here's what you can expect when you send us your application

    Step 0

    Tech Talent Hunt

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    Step 1

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    Step 2

    Uncovering Potential

    Your HR interview

    Step 3

    The Code Challenge or Technical Interview

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    Step 4

    Client’s Interview

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    Final

    The Last Piece of the Puzzle

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    Join our team of innovative thinkers

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    First Line Software, 2025

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