You should still sign an agreement laying out the relationship’s details. No legit SEO company, regardless of contract, should do SEO work without an agreement.
SEO works best when avoiding a long-term contract. Your SEO agency will focus on getting results, driving the SEO strategy, and ensuring they do what you hired them to do. There are many options when hiring an agency, and we believe that the best agencies work with clients without contracts when delivering SEO services.