This client & API are outdated. Please use mineskin.org / MineskinClient
Client for skulls.inventivetalent.org
Can be used to generate valid texture data from skin image files.
You can also use this online tool to directly generate skull data from images.
The API requires official Minecraft accounts to upload the skin textures.
If you own a Minecraft account you don't actively use and want to contibute to the API's speed, please contact me!