It is possible to watch the show Sons of Anarchy for free. Most websites that provide the entire series require a membership, but some websites do give a free trial for new members.
Hulu and Amazon Prime both provide all the episodes of Sons of Anarchy and also give a free one month trial for new members. A credit card is still required to sign up for both services. Watch-TV Series.net provides the episodes for free without an account, but per comments from members on the website, some episodes may be down or missing. The show is also available for purchase on iTunes, Amazon Prime, and Vudu.