http://gothub.r4focoma7gu2zdwwcjjad47ysxt634lg73sxmdbkdozanwqslho5ohyd.onion/unum-cloud/usearch
The resulting clustering isn't identical to K-Means or other conventional approaches but serves the same purpose.
Alternatively, using Scikit-Learn on a 1 Million point dataset, one may expect queries to take anywhere from minutes to hours, depending on the number of clusters you want to highlight.