On October 2, 1866, J. Osterhoudt received U.S. Patent No. 58544 on an Improved Method of Opening Tin Cans:

The first tin cans were so thick they had to be hammered open. As cans became thinner, specialized can openers were developed, such as the one disclosed in Ezra Warners’ U.S. Patent No. 19063, issued January 5, 1858:

Early can openers were complicated and difficult to use, leaving ample room for Osterhoudt’s simple key, which did require a specially constructed can.

On July 12, 1870, William Lyman received U.S. Patent No. 105346 on an improved Can Opener that used a rotating wheel to cut the can lid: :

T.A. Killman improved this design in 1925 by adding a crank operated knurled wheel to driving the cutting wheel around the top of the can, receiving U.S. Patent No. 1,558,372 on October 20, 1925:

A year later Charles A Bunker filed on the now familiar pliers-grip, top opening can opener, which was granted U.S. Patent No. 1,838,525 on December 31, 1931: