After having my back go out twice from sneezing, I asked my doctor about it. He told me this life changing tip which so far (6 yrs) has never failed. When you feel a sneeze coming on, pull your shoulder blades back and look directly up, you can sneeze as hard as you want in this position and you will be fine. In my experience just the looking up is usually enough to protect the back, the pulled back shoulder blades is just an added layer of protection.

My mistake, I only saw the option to buy on playstore. Also missed the open source on the dev page. Thanks for the heads up!

Conversation.im appears to be neither free nor open source.