Some of the cases date to the 1950s, The Guardian reported.
Joe Apps, manager of the Missing Persons Bureau, said the site is the first time families with missing relatives can do their own search.
"The aim of the new site is to bring closure to the families and friends of the people featured," Apps said. "With new unidentified person cases we rely on modern forensic techniques for identification but on older cases we look to use every tool available and believe that case publicity is the best chance of getting images recognized."
In some cases, the site shows clothing and other items such as the shoe found on a man floating off a Welsh island in 2003 or the clothes that belonged to a man found in the Thames River in London in 1989. A close-up of the left arm of a man found in a London street in 2007 shows distinctive tattoos.
Investigators say they also hope to use the site to find the families of living people who suffer from dementia or have lost their memories.