MessMoji - Emoji stickers for iMessages
Dango - Use emoji, stickers & gifs faster 😄 💬
StickerPop API - Embed all the best stickers and GIFs into your apps.
Stickered for Messenger - Add stickers to a photo and send them to friends
Sticker.Place API - Get stickers for your app
ISEBOX - ISEBOX offers content distribution and management solutions.