In Diablo III, the original maximum character level before expansion-specific progression was level 60.
The base game launched with characters able to advance through level 60. Reaching that level marked the end of ordinary character-level progression in the original release, although players could continue improving equipment and experimenting with builds.
The Reaper of Souls expansion raised the level cap to 70. It also introduced the Crusader class and added systems and content that changed endgame progression. As a result, level 60 is the historically correct cap for the original version, while level 70 is associated with the post-expansion game.
This distinction matters because references to Diablo III’s maximum level can depend on the version being discussed. The question concerns the base game before Reaper of Souls expanded the cap.