What characters and digits steam codes doesn't have?

In my list of keys I wasn't also able to find a "U", but that's all I guess.
What are you trying to do, brute force activate some steam keys? :D

im sitting on like 20 keys, im not gonna dig deep but your post made me interested in looking. i can confirm my keys contain no S,U, or 1. i did see zeros

I checked a list of something like 120 keys, and the only ones missing were: S, U, O and 1. Didn't realise this was a thing, but good to know

For anyone on SG that has won a lot of games and wants to look through a large list of keys, just go to your won page here and all the keys you won are listed.

You can use the find on page function of your browser to highlight all instances of something on the page and check each page of keys.

Edit: Done. I checked all letters and numbers against the almost 300 Steam keys I have won here and these are the results.

Confirmed characters used in Steam keys:
A through N
P through R
T
V through Z
numbers 2-9 and 0

O, S, U, and 1 are not in any of my almost 300 keys.

It actually wasn't that difficult since all the characters that are used showed in keys on the first page and I only had to go through the full 7 pages to verify that each missing character didn't show up anywhere.

Many characters that would print similarly to another character can be substituted as that other character.

If you have a code with a 0 (zero), for example, replace it with an O (oh), and activate the key. It should still work.

One of my key contains a letter S, and interestingly when i redeemed the game, i overlooked the code and typed "5" instead of "S" by accident, but the key still works.

Also, this old discussion has some good info, for the curious.

https://www.steamgifts.com/discussion/qVJ3U/how-many-steam-keys-are-possible

A-NP-RTV-Z02-9 are valid (in regex notation)

Though you can use (1, S, O are mapped to I, 5, 0 so they still do work)