Evolution of GitHub's Technology Stack

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GitHub recently turned 17 years old—but how did it start, how has it evolved, and what does the future look like as AI reshapes developer workflows?

In this episode of The Pragmatic Engineer, I’m joined by Thomas Dohmke, CEO of GitHub. Thomas has been a GitHub user for 16 years and an employee for 7. We talk about GitHub’s early architecture, its remote-first operating model, and how the company is navigating AI—from Copilot to agents. We also discuss why GitHub hires junior engineers, how the company handled product-market fit early on, and why being a beloved tool can make shipping harder at times.

Other topics we discuss include:

• How GitHub’s architecture evolved beyond its original Rails monolith

• How GitHub runs as a remote-first company—and why they rarely use email 

• GitHub’s rigorous approach to security

• Why GitHub hires junior engineers

• GitHub’s acquisition by Microsoft

• The launch of Copilot and how it’s reshaping software development

• Why GitHub sees AI agents as tools, not a replacement for engineers

• And much more!

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Timestamps

(00:00) Intro

(02:25) GitHub’s modern tech stack

(08:11) From cloud-first to hybrid: How GitHub handles infrastructure

(13:08) How GitHub’s remote-first culture shapes its operations

(18:00) Former and current internal tools including Haystack

(21:12) GitHub’s approach to security 

(24:30) The current size of GitHub, including security and engineering teams

(25:03) GitHub’s intern program, and why they are hiring junior engineers

(28:27) Why AI isn’t a replacement for junior engineers 

(34:40) A mini-history of GitHub 

(39:10) Why GitHub hit product market fit so quickly 

(43:44) The invention of pull requests

(44:50) How GitHub enables offline work

(46:21) How monetization has changed at GitHub since the acquisition 

(48:00) 2014 desktop application releases 

(52:10) The Microsoft acquisition 

(1:01:57) Behind the scenes of GitHub’s quiet period 

(1:06:42) The release of Copilot and its impact

(1:14:14) Why GitHub decided to open-source Copilot extensions

(1:20:01) AI agents and the myth of disappearing engineering jobs

(1:26:36) Closing

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The Pragmatic Engineer deepdives relevant for this episode:

• AI Engineering in the real world

• The AI Engineering stack

•  How Linux is built with Greg Kroah-Hartman

•  Stacked Diffs (and why you should know about them)

•  50 Years of Microsoft and developer tools

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See the transcript and other references from the episode at ⁠⁠https://newsletter.pragmaticengineer.com/podcast⁠⁠

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