What is SOI?

SOI stands for Single Opt-In, a term commonly used in affiliate marketing and lead-generation campaigns. When someone asks “what is SOI” or “what does SOI mean,” they’re referring to a process where a user submits their information—usually through a form—and is counted as a valid lead instantly, without needing to confirm their email or take an additional verification step. Because the user becomes a lead the moment they click “submit,” SOI offers fast conversions and high volume. However, it may produce lower-quality leads compared to systems that require extra confirmation, such as Double Opt-In (DOI).