ReadGoosebumpsFreeOnline.page.tl has the original 22 "Goosebumps" books by R. L. Stine available for reading online. However, the site does not have the books from "Horrorland" onwards.
The complete "Goosebumps" series is also available for purchase from Scholastic's website. The franchise originally began publication in July 1992, but the books were reprinted again in 2003. R. L. Stine still continues to publish new entries to the series; as of 2014, his newest book, "A Nightmare on Clown Street," is set to be released on Feb. 25, 2015. His newer books are not available online, but they can be found in bookstores.