Oyster, The "Spotify For Books," Is Taking On Amazon With E-Book Sales

Known for its unlimited e-book subscription service, Oyster is wading into the crowded e-book market against Amazon and Barnes & Noble.

Oyster, which has carved out its own subscription niche in the e-book market since it launched with 100,000 books in 2013, today offers subscribers a library of more than one million books, including the Harry Potter series. On Wednesday, Oyster announced it is heading into the general e-book sales market. This pits it against the e-book titans Amazon, Barnes & Noble, and Apple.