Söderköping is a locality and the seat of Söderköping Municipality in Östergötland County, Sweden. Located approximately 15 km southeast of the city of Norrköping, it had a population of 6,992 inhabitants as of 2010.
While its current population is relatively small, Söderköping is normally still referred to as a town for historical reasons. However, according to Statistics Sweden, the official designation of "town" is only applied to localities with more than 10,000 inhabitants.