Smooch.io (disclaimer: my company) has a really rich API for programming conversations.
You can use the API to converse with people on web chat, iOS/Android in-app chat, SMS, Facebook, Telegram, Viber, Twitter DM, WeChat, LINE+++ all through one single set of APIs. You can even send rich structured messages that are automatically translated into the best representation on each platform.
Thank you so much for smooch! I would highly recommend smooch.io for anyone looking to handle conversations on multiple platforms. The implementation with Facebook Pages is brilliant.
You can use the API to converse with people on web chat, iOS/Android in-app chat, SMS, Facebook, Telegram, Viber, Twitter DM, WeChat, LINE+++ all through one single set of APIs. You can even send rich structured messages that are automatically translated into the best representation on each platform.