| ID | Name | Type |
|---|---|---|
| #17583 | Office International | A |
| #17584 | Official Secrets | U |
| #10522 | Ofites Informatica | Z |
| #10523 | Oko | ? |
| #10524 | Okoloko Engineering Software | Z |
| #19760 | Oktogonia | P |
| #10525 | Olaf Astrand | + |
| #10526 | Olaf Hartwig | + |
| #10527 | Olaf Marohn | + |
| #22417 | Olaf Schröer | + |
| #10528 | Olaf Simone | + |
| #10529 | Olav Reinert | + |
| #10530 | Old English Software | Z |
| #18735 | Oldman | ? |
| #22298 | Oldsnapper39 | P |
| #10532 | Oldsoft | Z |
| #10531 | Oldřich Páleníček | + |
| #18105 | Ole Svendsen | + |
| #10533 | Oleg | + |
| #10534 | Oleg Anatolyevich Komarchuk | + |