BASiS delivers a rich collection of acoustic, upright, electric, and synth basses, all meticulously sampled to capture authentic performances. Its extensive library includes over 7 gigabytes of samples from iconic instruments such as Jazz Bass, P-Bass, Rickenbacker, and Musicman basses, alongside specialty models like Motown, gospel, Jaco's Fretless, and Macca's Hofner basses. Additionally, it features one upright bass, three slap basses, and more than a hundred synth bass patches ranging from vintage to modern and experimental sounds, providing a broad palette to enhance any musical style.

Each electric bass is sampled with both direct input and amped signals, allowing users to blend these sources seamlessly for a tailored tone. The upright bass offers a similar dual-input option, mixing DI with a tube mic capture. BASiS includes detailed controls for pitch bend range, pick and fret noises, release layers, and velocity adjustment, alongside an extensive effects suite featuring octaver, compression, saturation, distortion, modulation effects, and delay. These tools enable precise shaping of the bass sound to fit perfectly within any mix.

Performance is enhanced through innovative features such as a legato tool for fluid transitions and a customizable vibrato engine that mimics the nuances of real bass players. This vibrato is not based on standard LFOs but uses a sophisticated character model controllable via keyboard and interface. Randomized pick noises, release samples, and fret noises add further realism. Powered by the Kontakt Player 2 engine, BASiS integrates smoothly with major DAWs through AudioUnit, VST, and RTAS formats, while also functioning as a standalone application and within Kontakt 2 and 3 environments.