John Donnellan
Software Engineer
England, United Kingdom
Summary
👤
Senior🎓
Top SchoolJohn Donnellan is a seasoned software engineer with 11 years focused on building resilient, high-performance C# services and a long career at AT&T spanning technical support to labs engineering. He pairs solid systems engineering with a polyglot curiosity—regularly exploring F#, C and Scheme—to solve tricky correctness and performance challenges. His background includes operations and network roles, giving him a practical appreciation for operational reliability and maintainability in production systems. An Oxford mathematics graduate, he brings analytical rigor to algorithmic and design problems. Colleagues value his steady, learning-oriented approach and his ability to translate legacy telecom experience into modern service architectures. Outside typical engineering work he maintains a broad technical palette, often applying ideas from functional and low-level languages to improve robustness.
11 years of coding experience
21 years of employment as a software developer
Bachelor's degree, Mathematics, Bachelor's degree, Mathematics at University of Oxford
Stackoverflow
7,443reputation
812kreached
73answers
4questions
Github Skills (57)
octave9
dotnet9
unit-testing9
asp-net-core9
xunit9
csharp9
dotnet-core9
asp-net9
cprogramming-language9
roslyn-analyzer9
scheme-interpreter8
sicp8
ruby8
typos8
javascript8
Programming languages (12)
Github contributions (5)
codybartfast/aoc19
Nov 2019 - Nov 2020
Contributions:160 commits, 89 pushes, 11 branches in 11 months
codybartfast/aoc17
Dec 2017 - Feb 2026
Contributions:29 pushes, 1 branch in 8 years 3 months
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