For personal use, many players scan their own cards to create backups. Alternatively, high-resolution images of the cards are often available on in the game's "Files" section. Look for "Role Reference Sheets" or "Proxy Images."
The core rules are widely available in PDF format to help you understand role interactions and setup: Official Rulebook standard rulebook 1jour-1jeu one night ultimate werewolf print pdf upd
Sometimes users search for a "PDF update" because they believe the rules have changed. While the core rules of ONUW have remained stable, the has received errata (corrections) in newer print runs. For personal use, many players scan their own