Most developers today know Git.

But before Git became the industry standard, another Distributed Version Control System (DVCS) was competing closely with it:

Mercurial (Hg)

Interestingly, companies like Meta and Mozilla trusted Mercurial for large-scale engineering workflows involving massive repositories and thousands of developers.

That raises an interesting question:

If Git became the default standard, why did some elite engineering teams still choose Mercurial?

The answer reveals important lessons about:

developer experience

scalability

engineering workflows

ecosystem adoption

distributed systems thinking

What is Mercurial?

Mercurial is a Distributed Version Control System created in 2005.

Like Git, it allows developers to:

track code changes

collaborate across teams

create branches

merge changes

maintain project history

But Mercurial had a different philosophy:

prioritize simplicity and usability.

Why Developers Loved Mercurial

One thing many engineers appreciated about Mercurial…