Pinout!
The Raspberry Pi GPIO pinout guide.
This GPIO Pinout is an interactive reference to the Raspberry Pi GPIO pins, and a guide to the Raspberry Pi's GPIO interfaces. Pinout also includes hundreds of pinouts for Raspberry Pi add-on boards, HATs and pHATs.
Other Pinouts
We've created Pinouts for the Raspberry Pi Pico range of boards, too, you can find them here:
Plus chip planners for the RP2350A and RP2350B chips:
And some experimental pinouts, too: