Review on ESP-01 Wireless Transceiver Board 3.3V - 📡 4Pcs ESP8266 Serial WiFi Module for Arduino (Updated) by Michael Hicks

I've managed to get a few of these little boards to work with some difficulty, but reprogramming them has been a constant hassle. The same program/settings fail 4 or 5 times in a row before randomly working. There's no USB port or reset/program button, meaning you have to manually connect TX, RX, and RST, as well as 3.3V power. For about $1 more for a fee, you can get an ESP-12E with a Got a USB connector that can power the board and send programs, a regular Vin that accepts up to 12V, and a bunch of I/O pins. I was MUCH better with the 12E.