Carla is an audio plugin host, with support for many audio drivers and plugin formats. It has some nice features like automation of parameters via MIDI CC (and send output back as MIDI too) and full OSC control.
LinuxSampler - free, open source pure software audio sampler with professional grade features.
LinuxSampler vs Kontakt opinions
LinuxSample is simple and powerful
The intersection of sampling and synthesis. Falcon is a virtual instrument with 15 oscillators including analog, FM, wavetable, granular, … , 80+ effects, powerful modulation generators, scriptable event processors and more. Load as a stand-alone software or a DAW plug-in.
Soundplant is a digital audio performance tool that turns the computer keyboard into a versatile, low latency sound trigger and playable instrument. Via drag-and-drop, easily assign sound files of any format and unlimited size onto 72 keyboard keys, for hours of...
Pianoteq is a virtual piano that runs on your computer. Celebrated for reproducing with an unprecedented realism the behaviour and the sound of the acoustic piano, it offers superb dynamics, natural resonances and unique physical parameters.
VSampler transforms your PC into a 255 voice polyphonic software sampler that is able to use any recorded sound as a musical instrument. It provides all of the classical sampler features in excellent sound quality, and also offers you a multitude of unique new opportunities.This app doesn't have any features at the moment.