I have been using ThingSpeak for a while now and I decided to create my own API for logging IoT readings. The main reason for this is that ThingSpeak require me to manually set it up for each thing I want to log. I think this is tiresome and not as easy as I want it to be. Also I need one api key for each of my connected things. Last, but not least, I don't know how long my data is my data. They may "pull the plug" at any time and have me pay for the service (something I can easily understand).