Review on 📡 Izokee ESP-01 Serial WiFi Transceiver Module with USB Converter, Compatible with Arduino by Ronny Prather

As others have said, to write to the ESP-01 you need to add a switch to ground GPIO 0 at power up. Not only did I add the GPIO 0 button, I also added the reset button. With a little twisting finger maneuver I can 1) press the reset button, 2) press the GPIO 0 button, 3) release the reset button, then 4) release the GPIO 0 button. With this technique, I don't have to take the whole thing out and put it back in every time I want to write. Requires two buttons on the board and some 30 gauge winding wire. A 5-star module does not require mods. :)