SpriteSheet Packer is open source project.
Special thanks: musikov
Start date of development: 8.01.2014
Uses Qt - Digia Plc, LGPL license.
Having noticed interest cocos2d-x communities in sprite packer with GUI solved will share the development.
SpriteSheet Packer - utility which allows to you collect sprites in atlas.
Information about sprites frames can be exported in cocos2d-x format or, merely, in json-file. Also, exist ability to add own formats.
Firstly, this project was developed for own needs, but in certain moment I thought that it can be useful for other devs
I performed some fixes and placed it in open source.
Will be glad to hear feedbacks,
Best Regards, Alexey.