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Fractional Ruby on Rails developer for fast moving teams.

I'm Wagner Matos, a UK based software engineer helping startups, agencies, and SaaS companies build and maintain reliable Rails applications. Available for ongoing retainer or fractional engagements across the UK, US, and Europe.

You don’t always need to hire another engineer permanently. I can join your team part-time or on retainer to ship features, refactor legacy code, or keep your app stable and moving forward.

I integrate quickly, communicate clearly, and respect your team’s process. My goal is to make your life easier, whether that’s reviewing PRs, leading a small rebuild, or helping you plan technical decisions.

How I can help

  • Fractional Rails Development - Ongoing part-time engineering support for your product.
  • Technical Consulting - Architecture reviews, code audits, and mentoring.
  • Feature Development - Design and build new functionality with clean, maintainable code.
  • AI & Machine Learning Integration Add intelligent features to your apps: recommendation systems, natural language processing and AI-driven automation.
  • Maintenance & Support - Keep your app secure, up-to-date, and performant.
Get in touch

Inside ActiveRecord's Query Cache: When It Helps, When It Hurts

A few months ago, I was debugging a memory issue in a Sidekiq worker that processed CSV exports. The job was straightforward: iterate through a few hundred thousand records, transform them, and write to a file. Memory usage should have been stable...

Flask for Rails Developers A Gentle Introduction

Part 1 of a series on making the transition from Ruby on Rails to Flask If you've spent years in the warm embrace of Rails—where convention rules, generators abound, and rails new gives you everything but the kitchen sink, stepping into Flask can ...

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Recent Work

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Johnson & Johnson During the European Academy of Dermatology and Venereology (EADV) 2025 Conference, Johnson & Johnson Medical aimed to better understand how healthcare professionals interacted with their multi-zone exhibition booth. Traditional tracking methods lacked real-time visibility and were often dependent on unreliable event Wi-Fi and cloud connectivity.
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Johnson & Johnson During the European Academy of Dermatology and Venereology (EADV) 2025 Conference, Johnson & Johnson Medical aimed to better understand how healthcare professionals interacted with their multi-zone exhibition booth, so they’ve asked me to come with a solution that would provide real-time visibility while operating independently of Wi-Fi or cloud connectivity
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CoverageBook As part of CoverageBook’s Coverage Impact team, I helped improving the CSV ingestion and analytics pipeline, transforming an unreliable import process into a robust, self-healing data subsystem
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GSK The Touchscreen Vaccines Navigator is an interactive storytelling hub designed to reimagine how healthcare professionals explore vaccine science. Built for congress environments and medical exhibitions, it combines cinematic visuals with intuitive touch based navigation to transform dense clinical data into clear, self guided journeys. This experience was developed to showcase GSK’s leadership in adult immunisation through a seamless blend of storytelling, data visualization, and elegant interaction design, all packaged into a robust, offline ready touchscreen kiosk.