Mine are all indoor kitties--I rescued them from outside. I live on a busy street corner and it's just not safe out there.

Besides, if I had a cat door I'd end up with about 20 more cats living inside! I'm always finding my cats conversing through a closed window with a stray or feral. It's seldom the same kitty twice--there are so many homeless cats around, which breaks my heart. Angel (who never met a cat he didn't like) would invite every one of them in to play!