Keyboard switches for your regular or beige IIe
The Apple IIe keyboard has 5 kinds of switches that I know of, Alps long or short stem, or SMK long or short stem. Mitsumi long stem switches have also been confirmed(see last photo and last paragraph). Short stem switches used adapters or spacers to bring them up to a certain height. To remain on the same plane, broken switches should ideally be replace with like kind.
The first Apple //e's in 1983 (1982 motherboard) likely came with either of the two styles of short switches, or the Alps long switch. The //e's from 1985 (1984 motherboard) and up will likely have the SMK long switches and certainly from 1987 (1986 motherboard). Of course that depends on if it has it's original parts - someone may have replaced the entire keyboard.
Platinum //e keyboards use all black SMK switches and can be purchased here.
The easiest way to tell which switch you need is to remove a couple of different keycaps (to make sure that they all match in style). The stems on the switches are either round SMK (black or brown) or 3 sided Alps (usually cream colored). If there is a little spacer or adapter (black, brown, white or orange) left either on the switch or underneath the keycap, the switches are short.
SMK Brown stem switches with cream colored bases are low friction switches often used for the Spacebar and Shift keys. Tab, Control, Delete & Return may also use these.*There doesn’t seem to be any standardization on these switches even in Apple's own documentation. Some may have been replaced with black switches over time, and of course you can do that as well.
The Caps Lock switch, Reset switch and brown stem switches are sold separately. Caps Lock switches and many other parts come only 1 per keyboard, so supply is always very limited.
The keyboard power light, space bar spring, space bar stabilization bar, stabilization bar clips, and reset spring (Alps only) are available here.
Notes: Some Apple ][ and ][ Plus, Apple ///, Macintosh M0110 and Numeric Keypads may also use the Alps long or short stem switches.
Update: Mitsumi switches have been confirmed as yet another long stem switch on the Apple IIe. They look similar to the Alps long stem, but are white in color, and the stem has 4 sides "+" while the Alps is cream colored and the stem has only 3 sides. The Mitsumi switches were also used on the Macintosh Extended Keyboard M0110A.