I like Git's interactive/patch diff utilities!

Sometimes it's useful with any two files, not necessarily under Git.

One common example for me is to use it as a diff tool with Approval Tests.

Example

any two files

$ echo src > src; echo dst > dst

$ ./idiff.sh src dst
diff --git a/temp b/temp
index c419571..85de9cf 100644
--- a/temp
+++ b/temp
@@ -1 +1 @@
-dst
+src
(1/1) Stage this hunk [y,n,q,a,d,e,?]? y

$ cat dst
src