Dialogflow - Conversational UX Platform. (ex API.ai)
Slackmojis - A directory of the best custom slack emojis
Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
Discord Emoji - Iconfinder, but for emoji.
Botkit - Botkit is an open source developer tool for building chat bots, apps and custom integrations for major messaging platforms.
Emoji Builder - Create your own emoji in no time 💨