I'm always looking for cool sensors that would allow me to measure many things in the real world.

Unfortunately these days most of the sensors require you to use some crappy app or sign up to some service. I want none of that.

So, I started my search for cool sensors that also have open source.

Here are the ones I've found so far:

These two sensors are great, completely open, they use standard batteries that you can easily swap, and work great through Bluetooth.

Do you know of anything similar? It doesn't really matter that much what they measure, as long as they work great and are open source. Let me know here if you find something!