Aaron Winston interviews Anders Hejlsberg, creator of TypeScript, revealing how the language grew to become GitHub’s most-used language in 2025. The article details TypeScript’s evolution, its impact on AI workflows, and what this means for developers today.

TypeScript’s Rise in the AI Era: Insights from Lead Architect, Anders Hejlsberg

Introduction

TypeScript, founded in 2012 by Anders Hejlsberg, was created to solve scalability and maintainability problems in JavaScript for large codebases. In 2025, it became the most-used language on GitHub, surpassing JavaScript and Python—a milestone attributed to its combination of developer tooling, static typing, and seamless integration with modern frameworks and AI workflows.

The Early Bet on Types

Hejlsberg initially hoped that a quarter of the JavaScript community might adopt TypeScript. The project’s goal wasn’t to replace JavaScript, but to add structure, type safety, and better tooling for teams building large, complex systems.

“We didn’t set out to be everywhere. We just wanted developers to be able to build big systems with confidence.” — Anders Hejlsberg

As frameworks like React, Next.js, Angular, and SvelteKit began scaffolding with TypeScript by default, typed codebases became the norm. TypeScript’s familiar feel—like JavaScript with additional capabilities—helped drive adoption. Developers benefited from improved code safety, autocomplete, and easier refactoring.

Compiler Evolution and Performance

TypeScript’s compiler was initially self-hosted and written in TypeScript, which made it portable and accessible. However, performance needs led to a major rewrite in Go, delivering a 10x speed increase through native compilation and more effective concurrency. Despite the rewrite, the compiler’s behavior remains consistent—protecting backwards compatibility and user trust.

Open Source and the Evolution Mindset

Anders highlights open source development as “evolution captured in code.” TypeScript’s extensive GitHub history reflects years of transparent issue tracking, community contribution, and iterative design—a living record of how language features adapt and improve.

Data from GitHub’s Octoverse in 2025 underscores open source’s significance, with nearly a billion commits made in a single year.

The AI Effect on Language Choice

A notable trend in 2025 is AI’s influence on programming language popularity. AI models perform best in languages with abundant training data and strong type systems. TypeScript’s widespread usage and static types make it especially suitable for AI-generated or refactored code, offering more reliable outputs and better automation compatibility.

“AI’s ability to write code in a language is proportional to how much of that language it’s seen.”

AI’s involvement in coding moves types from being bureaucratic to being essential validators of correctness—an important advantage as humans and machines collaborate in building applications.

Developer Tools and AI Agents

The rise of large language models is redefining the tools developers use. IDEs are transforming into environments not just for humans, but also for AI agents that leverage typed structures for automated tasks. The Model Context Protocol initiative is mentioned as an example of how services can better support these new workflows, providing predictability and safety in AI-powered refactoring and code queries.

An Evolving Language for Evolving Workflows

TypeScript’s journey parallels Anders Hejlsberg’s career, from Turbo Pascal through C# to TypeScript. A consistent focus on empowering developers to write clearer code continues to shape the language’s path. With over a million developers joining GitHub and choosing TypeScript in 2025, TypeScript’s role in modern, AI-assisted development is more central than ever.

Conclusion

TypeScript’s story is one of steady adaptation—helping teams and now AI agents build, refactor, and maintain reliable software. The lessons from Anders Hejlsberg reveal the importance of community-driven evolution, backwards compatibility, and the growing intersection of types, AI, and open source in shaping how code is written and maintained.

Further reading: 2025 Octoverse report, Original GitHub Blog Post, GitHub Copilot

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