Element is described as 'cross-platform, modular AU/VST audio plugin host. Create powerful effects racks and instruments by connecting plugins to one another. Load graphs on the fly for quick access to your sounds'. There are eight alternatives to Element for Windows, Mac, Linux and BSD. The best alternative is Carla, which is both free and Open Source. Other great apps like Element are Giada (Free, Open Source), Reaktor (Freemium), Bidule (Paid) and VSTForx (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.
Native Instruments Reaktor is a virtual, modular synthesis platform. REAKTOR also provides a platform for modular synthesis in the form of Blocks – a range of sound generating and sound shaping modules.
Usine is a modular environment for live music and real-time installations. You can create and customize your live set to fit it exactly to your needs--spontaneous electronic music creation, including live sampling, effect processing, or sound design.
Freestyle is an innovative VST host for stage and studio. In Studio Split, layer and combine your VST instruments and FX to explore vast new sound design possibilities. Quickly organise and access your VST collection via the visual Plugin Browser.