"The Outsiders" by S.E. Hinton is available to read online on a few different web pages. The full book can be read at docs.google.com, as well as archive.org.
"The Outsiders" was published in 1967 and was written by Susan Eloise Hinton, who was 15 at the time she began writing the book. The coming-of-age plot follows two rival groups who are separated by their socioeconomic status. There is a murder between the two groups that causes the main characters to think about each other differently. The novel is also available online in audio format at ccusd93.org, as well as other websites.