Avid Space is described as 'Space is the ultimate Pro Tools reverb for music and post-production applications. From the largest concert hall to the densest plate reverb, Space delivers the pristine sound of natural reverb spaces with the familiar controls used in high end hardware reverb units'. There are more than 10 alternatives to Avid Space for Windows, iPhone, iPad, Mac and Linux. The best alternative is Audio Ease Altiverb. It's not free, so if you're looking for a free alternative, you could try Freeverb3 or Rooms!. Other great apps like Avid Space are Christian Knufinke SIR2 (Paid), Waves IR-1 (Paid), AudioReverb (Paid) and Mobile Convolution Reverb (Paid).
Freeverb3 is a sound processing library which includes sampling rate scaling enabled version of freeverb with some fixes, extended implementation of NReverb by CCRMA, implementation of impulse response convolution reverb, FIR filter constructor, band splitter, softknee/hardknee...
SIR2 is an easy to use native audio-plugin to use for high quality reverberation. It's available for the plugin formats VST and AudioUnit. It offers zero-latency processing with low CPU-consumption and non-destructive audio processing of impulse responses.
Wembley Arena. Grand Ole Opry. Sydney Opera House. CBGB’s. Birdland. Want to record in the world’s greatest venues? Now you can. IR1 puts the meticulously captured sound of these and many other renowned spaces in your hands.
LiquidSonics Mobile Convolution is an advanced, convolution reverb for use with Audiobus and Inter-App Audio hosts. It allows impulse responses to be stretched, cropped and envelopes to be applied for shaping the sound of a reverb in a very natural and musical way.