Bass Slapper 220.127.116.11 for Mac was available to download from the developer's website when we last checked. We cannot confirm if there is a free download of this app available.
Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe. The actual developer of this software for Mac is Waves Audio. The software lies within Audio & Video Tools, more precisely Music Production.
From the developer:
Waves Bass Slapper lets you recreate on your keyboard the realistic nuances of a dexterous bass player, with complete control over every note and articulation, including thumbing, popping, hammer-ons, pull-offs, open strings, legato sounds and dead notes.
Bass Slapper includes the world’s most extensive sample library of special bass guitar sounds, with slides, left- and right-hand mutes and harmonic strums.
You may want to check out more software for Mac, such as Drum & Bass Producer, inTone Bass Express or AV for Scarbee Rickenbacker Bass, which might be related to Bass Slapper.