RX888 Software
RX-888 get supported by various projects. You can choose one of these to fit your needs.
When you are on Windows, please remember you need to install driver first. Please check the instruction here.
GUI SDR Applications
HDSDR
HDSDR is 32-bit application which supports ExtIO. RX-888 has excellent ExtIO driver which is able to download from Github. 
SDR Console
SDR Console is rich feature SDR console on Windows. It has native support for RX-888. You can download it here. 
SDR#
It is a commercial software. It supports ExtIO so it can work with RX-888 well. You can download and trial here. Please place ExtIO binary into its installation folder to let SDR# detect RX-888. 
PhantomSDR
PhantomSDR is a web SDR which supports many users (>100 on a good setup). 
Interesting Projects
ka9q-radio
This is a project which is build a solution to receive multi signals at the same time. It makes RX-888 no more one receiver but many receivers. RX-888 is what author is using and testing in this project. Please check this excellent project here
rx888_stream
rx888_stream is a command line tool to use RX-888 to capture the signal data to disk. It is written in Rust. There is a old version in C here: (https://github.com/fventuri/rx888_stream)
Experiements
dual-polarization receiver for spectroscopy
Nathan Towne uses two RX888 MKII to setup a dual-polarization receiver for spectroscopy. He concluded:
the remarkable capability of the rx888mk2 receivers and USB3, spectroscopic receivers providing Stokes data product, and the potential for multi-antenna phased arrays.
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