SIR1 is a free convolution reverb.
The convolution reverb, that comes with reaper – or in the seperate plugin pack.
ReverberateLE is the free version of the Reverberate 2 and Reverberate Core.
Listing free reverb IRs – this list will be extended from time to time.
Quality might vary.
Hybrid (convolution/algorithmic) reverb that takes a different approach.