Nifty.org is a huge, free archive of adult sex stories which explores many different themes and various niches. The site has been around more than 20 years, it runs on donations, and specializes in LGBT stories (gay, lesbian, bisexual, transexual), but also contains bestiality.
There are more than 235,000 adult stories on Nifty from over 15,000 different writers and authors. Categories range from adult friends, authoritarian, camping, beginnings and bondage to historical, interracial, incest, and teen. Of course, this is just a taste of what can be found here.
Those of you who have a creative side can submit stories to Nifty for publishing after making sure to read the detailed submission guidelines. Others who are happy to just read will find a text-based website that has no ads, and looks very clean and simple. There are sections for new stories, authors, and an advanced search to help you find what you're looking for. Unlike some of its competitors, Nifty has made a site that looks and works well on mobile devices.
Nifty.org has a distinct and simple design without ads, and offers thousands of free LGBT sex stories. It has mobile support, some useful search tools, and you can even submit your own work.