This standalone battle royale mode is entirely free-to-play and shares the same launcher as MW3.
There are a few ways you can occasionally play portions of the game without buying it:
Activision frequently runs limited-time "Free Access" events, often around new season launches. During these periods, you can download a trial version from the PlayStation Store , Xbox Store , or Battle.net that typically includes a selection of Multiplayer maps and the full Zombies mode.