https://www.techradar.com/news/stumbleupon-has-stumbled-its-last

StumbleUpon, a content discovery engine from the early days of the internet that attracted 40 million users over its 16-year run, shut down Sunday. But, its successor will launch before long.

Before sites like Facebook, Tumblr and Reddit made it easy for people to curate their own bubbles of personally relevant content, sites like StumbleUpon helped people find popular web pages and receive recommendations for similar web pages.