Jon Sequeira
Principal Software Engineer at Microsoft
Seattle, Washington, United States
Summary
🤩
Rockstar🎓
Top SchoolJon Sequeira is a Principal Software Engineer with 14 years of experience leading and architecting developer tooling and cloud marketplace systems at Microsoft from low-level command-line APIs to large-scale billing platforms. He helped create and ship .NET Interactive, Try .NET, and Polyglot Notebooks—projects that blend language tooling, REPLs, and in-browser execution—while also driving the F# compiler and tooling as an engineering lead. Jon combines hands-on backend work (notably improving System.CommandLine and testing infrastructure in prominent dotnet repos) with systems design skills honed building CQRS/event-sourced services and composable pricing engines for Azure Marketplace. He’s equally practiced in lifting teams’ delivery through DevOps, TDD/BDD, and event-driven design, having coached small DevOps groups to operate services previously owned by much larger teams. Early career breadth—from e-commerce ERPs to deep Microsoft Office integrations—gives him a pragmatic bent for integrating legacy systems and shipping reliable production software. Based in Seattle, he pairs a creative-literature background with decades of engineering craft, bringing clarity and developer empathy to complex platform problems.
14 years of coding experience
22 years of employment as a software developer
B.A. English Literature & Creative Writing, B.A. English Literature & Creative Writing at Bard College
English, Spanish
Stackoverflow
546reputation
110kreached
11answers
2questions
Github Skills (23)
unit-testing10
net10
command-line-interface10
test-framework10
dotnet10
netframework10
dotnet-interactive10
asp-net10
dotnet-core10
command-line10
csharp10
system-commandline10
cli10
interactive-programming9
powershell8
Programming languages (12)
Github contributions (5)
dotnet/command-line-api
Mar 2017 - Jan 2023
Command line parsing, invocation, and rendering of terminal output.
Role in this project:
Back-end Developer
Back-end DeveloperContributions:7 releases, 573 reviews, 1246 commits in 5 years 11 months
Contributions summary:Jon primarily focused on making updates and improvements to the command line API, specifically within the context of testing. They replaced builders in tests and addressed code review comments. Their contributions are centered around the testing framework for the project, demonstrating a focus on improving and validating the core functionality. The user’s work indicates a commitment to ensuring the quality and reliability of the command line interface library.
argument-parsingsystem-commandlineparseroption-parsercli
dotnet/interactive
Jan 2020 - Jan 2023
.NET Interactive combines the power of .NET with many other languages to create notebooks, REPLs, and embedded coding experiences. Share code, explore data, write, and learn across your apps in ways you couldn't before.
Role in this project:Full-stack Developer
Full-stack DeveloperContributions:2 releases, 1599 reviews, 501 commits in 3 years
Contributions summary:Jon primarily contributed to the .NET Interactive project, focusing on improving the command-line tool and adding features related to value sharing. They implemented fixes to Try .NET references and package descriptions, as well as a change to enforce that directive aliases must start with % or !. Additional contributions include improvements to #!who and #!whos commands.
fsharpcode-sharemathematicadotnet-interactivedata-science
Find and Hire Top DevelopersWe’ve analyzed the programming source code of over 60 million software developers on GitHub and scored them by 50,000 skills. Sign-up on Prog,AI to search for software developers.