Works with CiviCRM 4.6. It might not be supported anymore.
Lists pairs of similar organisation names (differing by apostrophes etc) and allows the user to merge the records.
Screenshots (click to enlarge)
Since CiviCRM 5.x, extension releases compatible with CiviCRM 5.0 are compatible with 5.0 and later. An extension release compatible with 5.25, for example, means that it requires CiviCRM 5.25 or later.