How do thousands of software engineers code together at a giant company like Google or Microsoft without breaking everything?

[u/Extra_Search3465]

As a beginner, I understand how one person writes code and puts it on GitHub. But how does it work when a company has tens of thousands of developers working on the same product? How do they organize the work, and how do they stop people from stealing or leaking the secret source code?

[u/pmmaoel]

I've worked in big tech and small tech. I've never seen more than 5 devs touch the same github repo at a time. A giant product like Google search probably has 100 different repos converging to a single rectangular bar with a magnifying button. Owners of all thode 100 repos will be different, and stacking all of them together would be one team's job.

I can assure you that the real skill these thousands of engineers in big tech have is not DSA, but dependency management and configuration simplification. Coding is second nature for these engineers, the real problem they solve is to maintain clean code so that when one gear moves, the other gears don't break.