Anders Hejlsberg
Technical Fellow at Microsoft
Seattle, Washington, United States
Summary
🤩
Rockstar🎓
Top SchoolAnders Hejlsberg is a Technical Fellow at Microsoft and the lead architect of TypeScript, with a landmark career that includes designing C#, Delphi, and Turbo Pascal. With over four decades in software engineering, he combines deep language design expertise and compiler internals experience—recently contributing to a native port of the TypeScript compiler and core improvements to control-flow analysis and type handling. He began his career as a co‑founder of PolyData MicroCenter and served as Principal Engineer at Borland, shaping developer tooling and language ecosystems. Anders is active in the open-source TypeScript community, contributing tests and fixes across flagship repos like microsoft/TypeScript and DefinitelyTyped. Based in Seattle, he pairs pragmatic system-level thinking with a knack for elegant language abstractions that scale across millions of developers. An uncommon detail: he continues to work hands-on in compiler AST, binder, and checker implementations decades into a career of language innovation.
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 (19)
type-inference10
type-check10
flow-control10
abstract-syntax-tree10
testing10
typescript10
compiler-design10
go10
control-flow10
typescript-types10
type-checking10
typescripts10
javascript9
code-optimization9
type-definition9
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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