Podcast Summary: The Pragmatic Engineer
Episode: The Present, Past and Future of GitHub
Host: Gergely Orosz (Gergi)
Guest: Thomas Zumka, GitHub CEO
Date: June 18, 2025
Overview
In this episode, Gergely Orosz sits down with Thomas Zumka, CEO of GitHub, to explore the history, current state, and future direction of the platform. The conversation covers GitHub's enduring tech stack, remote-first culture, the business model, internal tooling, investments in security, hiring philosophies, AI-driven development (with a special focus on GitHub Copilot), how GitHub integrates with Microsoft, and perspectives on the evolving role of software engineers in the AI era. The discussion is rich in practical insights for software engineers, engineering managers, and tech leaders.
Key Discussion Points & Insights
1. The Evolution of GitHub’s Tech Stack
[02:33-05:56]
- GitHub remains one of the largest Ruby on Rails monoliths, with significant contributions from around 700 engineers ("We actually just passed 2 million git commits into the monolith" – Thomas Zumka, 03:16).
- Over the years, the tech stack has diversified:
- Frontend: Increased usage of React.
- Copilot API: Runs outside the monolith, written in Go for better API scalability.
- GitHub Actions: Built from legacy Visual Studio Team Services/Azure DevOps code, now evolving to support greater reliability ("goal of...getting to four nines and beyond" – Thomas Zumka, 03:59).
- Mobile Apps: Swift (iOS), Kotlin (Android).
- Infrastructure: Mix of own data centers and all major public clouds, with parts like Actions, Codespaces, and Copilot running on Azure.
Quote:
"It's still Ruby on Rails and I think it's still one of the largest Ruby on Rails applications... But we also have moved beyond just that one architecture."
— Thomas Zumka (02:58)
2. Self-Hosting and Cloud Strategy
[08:06-11:49]
- Early cost constraints and need for performance pushed GitHub to manage its own servers in commercial data centers, optimizing for file storage and networking requirements.
- Modern GitHub:
- Core platform still primarily runs in managed data centers.
- Newer services (e.g., Copilot, Codespaces) leverage Azure and other cloud providers ("...fully hosted on Azure for data residencies" for compliance – 10:29).
- "Boring" data sovereignty decisions (regional hosting, e.g. Germany, Sweden, Australia, US) are now strategic due to enterprise/government customer needs.
Quote:
"Storing Git data... is probably not like the best use case for cloud services, for cloud submitters that existed, you know, in 2008, 2009."
— Thomas Zumka (08:36)
3. Remote-First and Async-First Culture
[13:04-17:46]
- GitHub has operated as a remote and async-first company from early on, predating the pandemic.
- Communication is dominated by Slack and pull requests; email is rarely used internally ("All employees...work on GitHub; they have repositories to describe their team" – 14:23).
- Company announcements are PRs to an internal repo called "the Hub," shared via GitHub Pages.
- Town halls called "Get Together" rotate times to accommodate global staff.
- This culture aligns GitHub internally with both startups and open source projects.
Quote:
"We don't do company wide emails. Almost never we do an announcement on the Hub... and everybody can see, then we take the conversation there."
— Thomas Zumka (14:37)
4. Unique Internal Tools and Engineering Culture
[17:46-20:43]
- Early GitHub heavily emphasized in-house tooling, driven by a culture of letting employees work on passion projects.
- Haystack: Exception tracking (now replaced by Sentry).
- GitHub TV: In-house video streaming for town halls (now using Loom).
- Halp: Internal support system (replaced by Zendesk).
- Many of these tools inspired former employees to create startups.
- Open source products like Electron (from Atom), Desktop app, and GitHub CLI exemplify this culture of open, developer-first innovation.
Quote:
"GitHub...for many years didn't have a traditional IT infrastructure... because there was the belief we as GitHub can do it better than a tool that we can buy off the shelf."
— Thomas Zumka (18:16)
5. Security as Priority Zero
[20:43-24:59]
- Security is part of every employee’s responsibility: "who is on the security team? Every hubber raises their hand."
- Strong threat intelligence capabilities, aided by holistic Microsoft partnership, allow quick detection of security anomalies (e.g., flagging Heroku’s 2022 breach before Heroku itself found out).
- About 150 dedicated security staff (~10% of engineering force) with proactive vulnerability hunting (e.g., CodeQL usage in open source).
- Principle: "Cannot win the market if we lose the trust."
Quote:
"Security is part of our culture. We have the saying security is priority zero for everybody."
— Thomas Zumka (21:40)
6. Commitment to Hiring Junior Engineers
[24:59-31:55]
- GitHub has institutionalized early-career hiring with a large internship program since the pandemic.
- Junior engineers bring fresh skills (especially in prompting/AI), diverse perspectives, and energy.
- Experience-based bias: New grads are early adopters of AI and new tools, bringing prompt engineering and open source exposure to teams.
- Interns often get job offers, contributing significantly alongside senior talent.
- Hiring is not “backward thinking”; it’s essential for innovation and for GitHub’s future.
Quotes:
"We are excited about having this kind of like both junior and senior population in the company."
— Thomas Zumka (27:15)
"I think that's backwards in many ways... Actually folks that, you know, go to high school now... get to use AI much faster and… are, you know, taking this with an open mind."
— Thomas Zumka (29:00)
7. GitHub’s Early History and Developer-First Philosophy
[35:28-44:41]
- GitHub was born from the pain of early version control systems (SVN, TFS): centralization, complexity, poor UX.
- GitHub's early adoption driven by developer-first design, easy UX, and support for both public (free) and private (now also free) repos.
- GitHub innovated the "pull request" workflow (invented about a year after launch), democratizing contributions and making open source collaboration easier.
- The platform grew rapidly, earning the title “home of software developers.”
Quote:
"What always made GitHub GitHub is that they put the developers first."
— Thomas Zumka (36:10)
8. The Microsoft Acquisition & Its Impact
[52:04-59:28]
- Microsoft’s change in leadership (Satya Nadella) and open-source embrace paved way for 2018 GitHub acquisition.
- Post-acquisition principles:
- Developers First;
- Accelerate GitHub;
- GitHub Accelerates Microsoft.
- Investment: 700 → 3,000+ employees; ARR up 10x (from $200M/year in 2017 to $2B+/year by 2024).
- GitHub has kept brand, independence, and product focus post-acquisition (similar to LinkedIn/Minecraft).
Quotes:
"We set very early on clear principles… Developers First..."
— Thomas Zumka (57:07)
"GitHub innovated in the business model space as well... made private repositories free..."
— Thomas Zumka (45:37)
9. 2015-2020: “GitHub Stopped Shipping” & Reigniting Innovation
[61:42-66:20]
- Between 2015–2020, GitHub perceived as slow to ship; internally, new features were often enabled only for staff.
- Deep focus on reliability, security, and maintaining high community expectations led to cautious public launches.
- Post-acquisition, changes (free private repos, GitHub Actions, Sponsors, Copilot) accelerated, but took cultural and organizational work.
Quote:
"A culture where things were internally shipped but never made it to the public because everybody was worried, is that good enough to ship it?"
— Thomas Zumka (64:05)
10. Building and Launching GitHub Copilot
[66:51-71:57]
- Copilot genesis: Gained early access to GPT-3 through OpenAI/Microsoft partnership.
- Experimented with “text to code,” “code to text,” and “conversational coding.” Only “text to code” worked reliably.
- Rapid, positive internal adoption ("in the early days, 25% of the code in those files…" – 01:15).
- Went public beta in June 2021; over a million users in months.
- Copilot delivered significant productivity improvements (up to 46% of code written in certain scenarios by early 2023).
- Preceded ChatGPT launch and helped spark developer enthusiasm for AI pair-programming.
Quote:
"We realized together with OpenAI that it was able to write decent code… would not mix up the syntax between Python, Ruby and JavaScript… That worked so well that very quickly we saw our internal hubbers adopting the tool…"
— Thomas Zumka (00:00)
11. Copilot in 2023 and Beyond: "Refounded on Copilot"
[71:34-74:39]
- Zumka describes Copilot as foundational for GitHub’s next era, similar to how git enabled GitHub’s creation.
- "Refounded on Copilot" signals shift: human-AI collaboration as a core workflow.
- VS Code Copilot extension has been open-sourced to keep developer trust and platform openness.
- GitHub values reside in the platform, security, and collaborative layers—not in closed extensions.
Quote:
"Just as GitHub was founded on Git, today we are refounded on Copilot."
— Thomas Zumka (71:57)
"The ultimate value generation for these AI tools is in the platform...at the collaboration layer where people collaborate. And you see that with human to human collaboration. And we’re going to see that with human to agent collaboration."
— Thomas Zumka (76:23)
12. The Rise of AI Agents & The Evolving Engineer
[79:59-86:26]
- “Autonomous” AI agents aren’t fully autonomous: the engineer is still in charge of goal-setting and review.
- Agents automate “boring” or repetitive tasks (e.g., writing tests, documentation, bug fixes), but complex engineering, abstraction, and system design will rely on human oversight.
- AI raises the abstraction bar—engineers will solve higher-level problems and manage complexity, not become "just managers" of agents.
- New engineering skillsets: Prompting, system thinking, understanding how to combine AI tools effectively.
Quotes:
"I don’t like the term autonomous because I think autonomous...means the thing figures out itself what it should work on. That’s not how these things work."
— Thomas Zumka (80:52)
"The coding skill will be part of that engineering skillset. But ultimately, engineering means I can build a really large complex system and then evolve that into an even larger system next week."
— Thomas Zumka (86:20)
Notable Quotes & Memorable Moments
-
On Product Market Fit:
"Probably the product with the fastest product market fit nowadays... It was unheard of how quickly it spread like wildfire."
— Thomas Zumka (38:09) -
On Open Source and Business Models:
"GitHub invented a version of the freemium model that is not ad based..."
— Thomas Zumka (45:37) -
On Security Culture:
"When the question is asked who is on the security team, every hubber raises their hand."
— Thomas Zumka (21:40) -
On Copilot’s Impact:
"Very quickly we saw our internal hubbers adopting the tool, giving it really high scores, saying, this is great, I want to keep using this."
— Thomas Zumka (00:54) -
On AI and Hiring:
"If you want to get a job in a tech company very soon, you’re going to be asked to show your prompting skills, your copilot skills..."
— Thomas Zumka (33:07)
Important Timestamps
- 00:00 – Copilot’s beginnings; internal productivity gains
- 02:58 – Tech stack: Rails monolith and microservices
- 08:36 – Early infrastructure decisions, own data centers
- 13:41 – Remote and async-first work culture
- 20:43 – Security as priority zero
- 24:59 – Investment in hiring juniors and interns
- 35:28 – Founding story of GitHub
- 43:33 – Invention of the pull request
- 52:24 – Microsoft acquisition: intention and context
- 61:42 – Stagnation (2015-2020) and internal vs. public innovation
- 66:51 – Copilot timeline and adoption
- 71:57 – "Refounded on Copilot" – future vision
- 74:39 – Open sourcing Copilot VS Code extension
- 79:59 – The future role of AI agents and engineers
- 84:43 – GitHub’s massive traffic and scaling challenges
- 86:26 – Final takeaways: AI raises the abstraction for devs
Final Takeaway
GitHub’s journey from a scrappy, developer-first Rails monolith to an AI-powered, globally distributed platform sets the stage for the next era—where engineers and AI collaborate closely, but human creativity, judgment, and system design remain central. The platform’s commitment to open source, security, and hiring junior engineers reflects a deep belief in community-driven progress. Whether you’re a developer, leader, or engineering student, this episode is a masterclass in how software platforms—if they keep evolving and listening to their communities—can reinvent themselves for every new generation of builders.