Is there a free alternative to cleverbot/cleverscript?

Is there a free alternative to cleverbot/cleverscript?

What are the best dialog system APIs for the Internet of Things?

Found so far:

• allthingstalk.com
• api.ai
• ask-ziggy.com
• botlibre.com
• chatbot4u.com
• mondobot.com
• pandorabots.com
• wit.ai