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I think that Visual Studio has it on the right hand side by default, but that's the only editor I can think of that does it.

It does not have it by default on the right, but you can move it yourself.

Visual Studio Code does not. But Visual Studio does.

Nowadays, Visual Studio on the old days had it on the left by default.

Actually I don't remember any longer when they changed, maybe VS 2010 WPF rewrite.

IIRC they brought it into line with the old SQL Server Management Studio (SSMS), which always had the explorer on the right.