gpSonic Level Ripper
From Sonic Retro
gpSonic Level Ripper is a Windows program made by Damizean using the Nemesis Sonic Hacking guide documentation that rips 16x16 tile mappings and metablocks into Windows Bitmap format, and was originally made to rip levels for his old defunct project gpSonic.
It supports Sonic 1, Sonic 2, Sonic 3, Sonic CD and Sonic Crackers savestates, although support for Sonic CD save states is very poor and only supports 16x16 mappings. It has been long discontinued, but it's still good for its purpose.