As the name, Feedspot is a spot of feeds, or we can say that it is an RSS reader.
You can not only search within the feeds you follow, but also through the whole Feedspot database, which has collected thousands of feeds from different websites and blogs about technology, comics, psychology and many other topics.
Besides, you can also track the search keywords, like what you can do with Twitter saved searches.
You can automatically post your shared items and/or favorites to Evernote, Facebook, Twitter and/or some other sites of your choice.
And you can also follow some other Feedspot users and check out what they have shared.
When search for something, you will see some related public folders if there are any, which you can follow and check out the RSS feeds inside them.
Besides, you can also create and share your folders with other users.
But Feedspot offers both free and paid services, and for the free one, there are some limits, such as that there will be ads, there will be only a few results for your search, there will be no smarter searching ("quickly find articles you are looking for in half the time using Advanced Search"), so on and so forth.
Although Google Reader was 100% free, its usage "had declined over the years", so RSS readers are not so popular any more, and I do not think there will be too many people to buy the Feedspot paid service, what do you think?