It’s a cheerful orange giant stuffed with fan fiction and smileys which can garner a billion reads for an erotic One Direction story – scoring 25-year-old Texan Anna Todd a six-figure publishing deal in the process. But Wattpad also has a serious side as a thriving culture of original writing, with a small but steady flow of authors finding mainstream success with Big Six publishers such as Random House and Harper Collins. Half a dozen of these authors are getting together in the real world mid-December, at Wattpad’s first UK convention. The site has attracted more than 40 million users around the globe. No surprise, then, that Amazon has decided it wants a piece of the action.

The internet shopping site has just launched its own social reading and writing platform, Kindle WriteOn, a move characterised by Reddit co-founder Alexis Ohanian as “trying to eat [Wattpad’s] lunch”. WriteOn is currently in invite-only beta mode, but all you need for access is the online equivalent of a Masonic handshake – a code passed to you from someone on the inside.

On first impressions, it looks remarkably like Wattpad, just less orange. But WriteOn is making a clear play for writers of original fiction with publishing ambitions. It bills itself as “a story lab” where “you can get support and provide feedback at every stage of the creative process.” And while Wattpad’s reader comments tend to be short and sweet, WriteOn is designed for in-depth critique. Feedback submissions have a whopping 10,000-character limit. Imagine how many :D and <3 you can get for that.

So far the fan fiction category appears unloved – “0 reads 0 likes 0 follows 0 comments” is the pitiless tally of a bowtie-themed “crossover” between Dr Who and the Thor movieverse. Perhaps the invitations haven’t yet reached fan fiction fans, or maybe the problem is the space Amazon built for fanfic writers last year: Kindle Worlds.

Kindle Worlds peddles that joyless oxymoron “licensed fan fiction”, whereby fans adhere to rules set by the copyright holder and sell their story through Kindle. All three get a cut of the sale. Yet 18 months after Kindle Worlds launched, only 679 stories are available for purchase. Amazon assumed that fanfic writers wanted a marketplace, when what they love most is a no-rules playground.

With 150m Amazon accounts already in existence, the retailer will be hoping WriteOn builds on the success of its Kindle Direct Publishing platform for indie authors, adding a social element to a publishing phenomenon.

Wattpad faces the opposite challenge: to deliver a return on investment for backers who earlier this year put in $46m (£29m) of fresh funding. For now, it’s focused on doing that the way it knows best: socially. “Our near-term priority should be building a great social product and growing the global community of Wattpadders,” CEO and cofounder Allen Lau tells me. His goal is to take the site to a billion users.

Though ambitious, that might just be achievable. As an enthusiastic Wattpad user myself, I can testify to the speed with which the site draws you in. As investor Tripp Jones of August Capital says by email, it exerts “a powerful network effect … which makes the company extremely difficult to compete with, even for competitors with next-to-infinite resources”. Who could he possibly mean? Or as Wattpaddicts might say: “(¬_¬) LOL.”