Spine - Spine is 2D animation software designed specifically for software and game development.
Free Texture Packer - Free Texture Packer is an open source tool that allows you to pack multiple images into one atlas for you games or sites.
Synfig Studio - Just another WordPress site
ShoeBox - Free unlimited photo storage, so you can rediscover your photos anywhere. Available for iPhone, iPad, Android, Mac and PC.
Live2D Cubism - Live2D is the world's first drawing technology to enable 3D rendering of 2D images.
Sprite Sheet Packer - Sprite Sheet Packer is online that you can easily use to pack sprite sheets, including data formats for CSS, LESS, and Phaser.