vPlayer by Digital Brain Instruments is described as 'vPlayer is a standalone software developed for quick testing new vst/au instruments without the need to use any DAW'. There are more than 10 alternatives to vPlayer by Digital Brain Instruments for Windows, Mac, Linux and BSD. The best alternative is Carla, which is both free and Open Source. Other great apps like vPlayer by Digital Brain Instruments are Cantabile (Paid), VSTHost (Free Personal), Blue Cat's PatchWork (Paid) and Bidule (Paid).
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.
NDLive turns your laptop into an FX rack at low latency. NDLive is a platform that allows you to safely use the VST NeoductionTools plugins and third parties plugins with the reliability of your regular DAW and the latency of your live mixer.
Lite version of inTone 2, a live performance fx processor and virtual instrument host. inTone 2 Solo only limited in track numbers, not functionality. Almost 40 FX plugins, 1 track player, 1 audio track, 1 instrument track, 1 AUX and 1 master chain.
NanoHost is not a synthesizer. It is a free, minimalist host application for Windows that can load VST-synths. Furthermore, it can act as a wrapper which converts VST-synthesizers into standalone applications.