It currently says it has the "Hipparcos-Yale-Gliese" database, with 119,614 stars and the "Tycho-2/Gaia" subset with 118,971 stars. That seems pretty close to the numbers quoted in the demo.
I used it previously for a matrix math conversion project translating the NIST JAMA library into a Javascript library.
If interested, the test page as a githack link can be found here. Click the "Run 3D Ellipse Fitting on Nearby (100 LY) Stellar Data". My example only uses the 25,000 out to 100 LY.
