Sprout Builder is described as 'web-hosted, visual authoring solution that allows creative professionals to quickly and easily create branded, rich-media content and widgets'. There are six alternatives to Sprout Builder, not only websites but also apps for Windows and Mac. The best alternative is Adobe Animate. It's not free, so if you're looking for a free alternative, you could try NewsGator Widgets or Transpond. Other great sites and apps similar to Sprout Builder are KoolMoves (Paid), Artist Code (Paid) and Aphalina Animator (Paid).
Artist Code is an intuitive software for creating animation ( Movie, Animated Gif, Images) only by coding, it allows you to add image, text and pixels and place them with simple script offering you a fun and unlimited way to create whatever you want.