Monorepo Terms:

Multirepo Terms:

There is also a hybrid approach of some monorepos mixed with multirepos.

Monorepo disadvantages

Git source control is often used, and it does not scale at massive code levels and may require customisation to do so (not many people will hit this problem)
Security is harder. GitHub can let you restrict access to certain parts of a repo, but everyone can read all.
Can make it to easy to couple code for the unwary.
Large code bases can slow down (maybe some monorepos can restrict this problem with partial loading)
- builds
- editing tools
some tooling like Continuous Integration does not support monorepos well, or you pay extra.

Monorepo advantages

Easier to download all the code
Easy to search all the code (unless your monorepo is so large you only get access to virtual areas of it and hence not all is local)
- Features like organisation searches in GitHub can potentially give you this level of searching in multirepo without need to clone.
Refactoring is easier (if your monorepo and programming language/editor support it)
you can create branches across a whole piece of work (in different areas) and determine if it works which is generally harder to do in multirepos and there is not a lot of widely used tooling to support this as far as I can tell.
some monorepo tools can determine a graph of dependencies and how changes may require incremental builds or running of tests etc.
it may be easier to reuse pipeline structures within a monorepo

Tools for monorepo

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