Anders Hejlsberg
Technical Fellow at Microsoft
Seattle, Washington, United States
Summary
🤩
Rockstar🎓
Top SchoolAnders Hejlsberg is a Microsoft Technical Fellow and Software Architect based in Redmond, Washington, with 13 years of experience and the lead architect of TypeScript. He is the original designer behind C#, Delphi, and Turbo Pascal, bringing a rare history of language-first thinking to modern developer tooling. On GitHub he contributes deep, hands-on fixes to the TypeScript compiler—working on control flow analysis, template literal types, and unique type-parameter naming—while also adding robust tests. He played a core role in porting the TypeScript compiler to Go by implementing AST node structures and refining binder/checker logic. Equally comfortable in QA and core engineering, he bridges language design vision with meticulous, production-grade implementation across large open-source ecosystems.
13 years of coding experience
17 years of employment as a software developer
Danmarks IngeniørakademiHigh School, High School at Holte GymnasiumTechnical University of Denmark
Github Skills (24)
typescript310
type-inference10
type-check10
abstract-syntax-tree10
testing10
flowcontrol10
typescript10
typescript210
compiler-design10
go10
control-flow10
typescript-types10
type-checking10
typescripts10
controlflow10
Programming languages (3)
Github contributions (5)
microsoft/TypeScript
Jul 2014 - Jan 2023
TypeScript is a superset of JavaScript that compiles to clean JavaScript output.
Role in this project:
Back-end Developer
Back-end DeveloperContributions:371 reviews, 4056 commits, 1636 PRs in 8 years 7 months
Contributions summary:Anders primarily contributed to the TypeScript project, as shown by the commit messages that directly address problems in the source code. The user demonstrated expertise by improving unique type parameter naming and adding tests. The user also made numerous changes related to control flow analysis, including handling of template literal types, and fixing issues with annotations.
typecheckerjavascriptcleantype-checksuperset
microsoft/typescript-go
Mar 2025 - Mar 2025
Staging repo for development of native port of TypeScript
Role in this project:Back-end Developer
Back-end DeveloperContributions:20 reviews, 20 PRs, 14 pushes in 18 days
Contributions summary:Anders contributed to the initial port of the TypeScript compiler, focusing on core aspects of the compiler's internal structure. This primarily involved the creation and implementation of fundamental AST node structures and related functionality within the compiler. The contributions also encompassed modifications to the binder and checker components, demonstrating a focus on integrating and refining the compiler's type-checking mechanisms. Furthermore, the user participated in refactoring and formatting the existing codebase.
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