ChatAnalytics is an open source app that runs 100% in-browser to analyze chat exports from multiple platforms (currently Discord, Telegram and WhatsApp). You get in a single HTML file statistics and cool graphs that you can easily share! Demo available!
I tried to use it a couple of times and received an error on upload of documents with no instructions on what to do next.
After a while I tried uploading it from a different file location and it worked. Fun results!