Santiago Fernandez
Principal Software Engineer at Microsoft
Greater Seattle Area United States
Summary
🤩
Rockstar🎓
Top SchoolSantiago Fernandez is a Principal Software Engineer in the Greater Seattle area with nine years at Microsoft, progressing from intern to principal while focusing on .NET runtime, tooling, and build infrastructure. He is a pragmatic back-end engineer who has improved core libraries (System.Reflection.Metadata, System.Runtime, Mono) and contributed to high-profile Microsoft open-source projects like dotnet/runtime, winforms, and arcade. Santiago’s work spans bug fixes, nullability modernization, AOT/runtime changes and build/Helix automation—demonstrating both deep systems knowledge and attention to build/test reliability. He has also driven maintainability improvements such as package restructuring, signing for NuGet publishing, and test stability across platforms. Comfortable operating at the intersection of runtime internals and CI/CD, he brings a developer-first mindset to large codebases. An often-overlooked strength is his steady focus on annotation and type-safety improvements that reduce runtime errors and make massive repos easier to evolve.
9 years of coding experience
10 years of employment as a software developer
Ingenieria en Tecnologias Computacionales, Ingenieria en Tecnologias Computacionales at Tecnológico de Monterrey
Stackoverflow
36reputation
347reached
3answers
0questions
Github Skills (41)
reflection10
debug10
runtimes10
language-ext10
msbuild10
testing10
net10
dotnet10
run-time10
metadata10
cicd10
windows-forms10
asp-net10
runtime-compilation10
automation10
Programming languages (11)
Github contributions (5)
dotnet/corert
Dec 2016 - Sep 2019
This repo contains CoreRT, an experimental .NET Core runtime optimized for AOT (ahead of time compilation) scenarios, with the accompanying compiler toolchain.
Role in this project:
Back-end Developer
Back-end DeveloperContributions:43 commits, 8 PRs, 5 pushes in 2 years 9 months
Contributions summary:Santiago's contributions focused on porting and implementing features in CoreRT, a .NET Core runtime optimized for AOT scenarios. They added the `AddOrUpdate` method to `ConditionalWeakTable`, implemented the use of `CreateFile2` in place of `CreateFile2FromApp`, and made changes related to type forwarding and annotations for nullable strings and other exception types within the core library. These changes demonstrate involvement in modifying core functionality within the .NET runtime.
dotnetcompilationahead-of-timeruntimetoolchain
dotnet/arcade
Mar 2017 - Aug 2021
Tools that provide common build infrastructure for multiple .NET Foundation projects.
Role in this project:Automation Engineer / Build & Release Engineer
Automation Engineer / Build & Release EngineerContributions:63 reviews, 69 commits, 109 PRs in 4 years 5 months
Contributions summary:Santiago's commits primarily focus on improving the build and test infrastructure for the `dotnet/arcade` repository. They have made changes to the build scripts and task definitions within the Helix SDK, including adding functionality to handle retries and download results. The contributions involve integrating with Helix and updating the code analysis tooling. Furthermore, the user addresses logging improvements and resolving potential deadlocks in the UAP runner.
dotnetinfrastructurefoundationcsharpdotnet-core
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