What Is the Modern StumbleUpon?

Economics has the concept of a "substitute good": a product or service that consumers use as a substitute for another (StumbleUpon), to achieve the same outcome.

In StumbleUpon's case, the product is the output - a steady supply of fresh, reasonably relevant/somewhat curated links - not a specific mechanism for doing that. In those terms, I'd argue that the biggest substitute is Reddit.

Obviously the curation/relevance process is different, but many subreddits and Reddit itself deliver the same output that StumbleUpon did.

I never liked SU. One out of every 10 links was interesting and I was genuinely surprised one out of every 100 links. It was taken over by spammers trying to get traffic. Hackernews, Reddit, & Pinboard are my go-to staple for articles & sites that I am interested in, and don't have to 'roll the dice' to get a good article, I simply hand pick the page.