Available for freelance work
Legacy systems modernization specialist_
I help businesses bring outdated systems into the modern era. .NET migrations, API integrations, and process automation that actually works.
// 01
I'm a developer who enjoys the parts of software most people avoid: understanding old systems, figuring out why they were built that way, and bringing them into the present without breaking what already works.
My day-to-day is modernizing legacy applications, migrating codebases to .NET, and building the integrations that keep businesses running. I care about writing code that other developers can read six months from now, and about shipping things that actually solve the problem.
On the side, I study game development. It's where I got started and it's still what I love most about programming, the feeling that you're building something people will actually experience.
// tech I work with
// 02
What I can help you build. Every project is different, so if you don't see exactly what you need, reach out anyway.
Modernize outdated systems without losing what already works. From VB6, WinForms, or old .NET Framework to current .NET.
Backend systems, APIs, and business applications built on modern .NET. Clean, maintainable, and ready to scale.
Connect your systems with third-party services and internal tools. From payment gateways to internal ERPs.
Turn manual, repetitive workflows into reliable automated processes. Save hours of your time and reduce error.
Have something else in mind?
Let's talk about it// 03
Real projects, real clients. Names are anonymized to respect confidentiality — the technical details and impact are not.
#01
2026
AVG Sistemas
A modern web platform for customs brokers, built on top of a 20-year-old local database — without touching it.
AVG Sistemas needed to modernize the pre-María workflow that their customers rely on daily. The challenge: the underlying customs data lives in a local SQL Server database on every broker's PC, and it can't be migrated or exposed to the internet. I designed a hybrid architecture with a secure Windows agent per broker and a cloud web platform that reads and writes to those local databases in real time — turning a desktop-only workflow into a multi-tenant SaaS.
15 min → 2s
per régime change
30 min → 10s
bulk data entry
Zero
DB exposure
// stack
#02
2026
Customs Brokerage Firm
Replaced a 20-process legacy system with a single, modern service.
A customs brokerage firm was running 20 parallel legacy processes to sync with the national customs authority. Slow, memory-heavy, and impossible to monitor. I designed and built a unified .NET service that replaced all of it, with automatic failure detection and recovery.
2h → 10s
per sync cycle
16 GB → 300 MB
RAM (from GBs)
24/7
in production
// stack
#03
2026
Customs Brokerage Firm
Modernizing critical operations without touching the legacy system.
A daily task that consumed hours of manual work: notifying every client when their shipment was released. I built a modern web app that reads directly from the legacy database (read-only) and automates the whole process, without changing a single line of the original system.
10 minutes → 25 seconds
per notification
Zero errors
in critical data
Multi-tenant
ready
// stack
#04
2025
Growin Consulting | Public-Tender Platform
Feature delivery and performance work on a 10-year-old codebase.
Ongoing work on a legacy PHP platform with no documentation and a proprietary in-house framework. I reverse-engineered a broken production scraper, built a tiered access system for new AI features, and audited the codebase for performance bottlenecks. Zero downtime, incremental delivery.
100% → 0%
scraper failure rate
3 tiers
access system
Zero downtime
deployments
// stack
More projects available on request
Check my GitHub ↗// 04
Where I started, and still my favorite part of programming. Currently studying game development at UTN Buenos Aires while working professionally in software.
CART #01
Phsycological horror game where the character get inside a loop and paranormals things follows him.
CART #02
Inspired by fears to fathom 1st where you need to resolve puzzles to scape from the house while a little child wants to kill you
More cartridges loading...
New game dev projects coming as I progress through the program.
// 05
Have a project in mind? Need help modernizing something old, or building something new? Drop me a message.
NEW MESSAGE
// or reach out directly
bautistafbuteler@gmail.com
GitHub
@BautistaFernandez
bautista-fernandez-buteler
STATUS
Available for new projects starting Q1 2026