Building Claude Code with Boris Cherny

Key takeaways

Boris Cherny's journey into software engineering was driven by practical needs and curiosity, leading to significant contributions at Meta and Anthropic.
Cloud Code's evolution from a side project to an integral tool exemplifies the power of adaptability and innovation in software development.
AI tools like Cloud Code change the role of engineers, allowing more focus on product and user experience rather than just writing code.
A hybrid approach to code review that combines automated checks with human oversight ensures high quality in a fast-paced engineering environment.
Anthropic's collaborative culture enhances product development, with engineers, designers, and product managers working closely together.
Claude CoWork simplifies interaction with coding for non-engineers, showcasing the shift toward making software development accessible to broader audiences.
Essential skills for future engineers will include adaptability, curiosity, and a willingness to engage across traditional role boundaries.

Summary

Boris's Journey to Anthropic

Boris Cherny, the creator and head of Claude Code at Anthropic, shares his journey into tech, starting from his teenage years selling Pokémon cards on eBay and accidentally learning HTML. He discusses how practical coding has always been his focus, leading to multiple startups before joining Meta (now known as Facebook), where he had a prolific career as a software engineer.

The Evolution of Cloud Code

Boris dives deep into the origins of Cloud Code, which began as a side project and evolved into a critical tool at Anthropic. He discusses the development process, internal debates about releasing the tool, and how it revolutionized workflows at Anthropic, allowing engineers to ship code efficiently with minimal manual intervention.

Workflows and the Role of AI in Engineering

The conversation focuses on Boris's daily workflow, showcasing his efficient process of managing multiple parallel requests through Cloud Code. He highlights how the tool empowers engineers to shift roles and responsibilities in software development, moving more towards product-oriented thinking.

Code Review and Verification Patterns

Boris discusses the unique approach to code reviews at Anthropic, where Cloud Code is integrated to automatically review code and run tests. This is enhanced by a combination of automated linting and human oversight, ensuring high-quality code is delivered even in high-velocity environments.

Anthropic's Engineering Culture

The podcast explores the culture at Anthropic, with a focus on collaboration across disciplines, including engineers, designers, and data scientists. Boris highlights the impact of this collaborative approach on product development and emphasizes the importance of adaptability and curiosity in the tech industry.

The Launch of Claude CoWork

Boris introduces Claude CoWork, a new tool developed for non-technical users, emphasizing its ease of use and safety. He discusses how it was built rapidly in response to user demand, transforming how non-engineers interact with coding and automation.

Looking Ahead: Skills for Future Engineers

The conversation touches on the essential skills that remain valuable as engineering evolves. Boris emphasizes the importance of adaptability, curiosity, and the fusion of skills across traditional roles. He raises concerns about the security and ethical implications of AI advancements in software engineering.

Show notes

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Boris Cherny is the creator and Head of Claude Code at Anthropic. He previously spent five years at Meta as a Principal Engineer and is the author of the book Programming TypeScript.

In this episode of Pragmatic Engineer, we went through how Claude Code was built and what it means when engineers no longer write most of the code themselves.

We discuss how Claude Code evolved from a side project into a core internal tool at Anthropic and how Boris uses it day-to-day. We go deep into workflow details, including parallel agents, PR structure, deterministic review patterns, and how the system retrieves context from large codebases. We also get into how Claude Cowork was built.

As coding becomes more accessible, the role of engineers shifts rather than shrinks. We examine what that shift means in practice, which skills become more important, and why the lines between product, engineering, and design are blurring.

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Timestamps

(00:00) Intro

(11:15) Lessons from Meta

(19:46) Joining Anthropic

(23:08) The origins of Claude Code

(32:55) Boris's Claude Code workflow

(36:27) Parallel agents

(40:25) Code reviews

(47:18) Claude Code's architecture

(52:38) Permissions and sandboxing

(55:05) Engineering culture at Anthropic

(1:05:15) Claude Cowork

(1:12:48) Observability and privacy

(1:14:45) Agent swarms

(1:21:16) LLMs and the printing press analogy

(1:30:16) Standout engineer archetypes

(1:32:12) What skills still matter for engineers

(1:35:24) Book recommendations

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The Pragmatic Engineer deepdives relevant for this episode:

• How Claude Code is built

• How Anthropic built Artifacts

• How Codex is built

• Real-world engineering challenges: building Cursor

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