I have looked at other responses and each layout is a little different. Looking to connect a Smart Thermostat and need to know where to connect the Blue wire at the Furnace. See the attached picture. Lots of possibilities. Thanks for the help and guidance.
The wire nut on the far right is your common. Test it before you power up your stat. You can test it by attaching test leads from the red to the blue coming from the furnace. You should get 24v.