Review on HiLetgo PCF8574 PCF8574T IO Expansion Board I/O Expander I2C Evaluation Development Module (2pcs) by Joshua Garris

If you need more I/O pins on your Arduino/ESP, look no further than here. This module gives you 8 digital pins without using any pins other than your I2C bus and power supply. I'm working on hooking mine up to an 8 relay module. Since I work with high voltage I have not posted any pictures yet. :) Pro tip: As others have said, the I2C address can be 0x38 or 0x20. If you have an I2C scanner sketch (and you should) it will take you a minute to figure it out. Do not worry. Change is part of life.