The ESP-01S is an affordable solution for connecting your Arduino to Wi-Fi, featuring minor improvements in the PCB compared to the standard ESP-01 module. Utilising the ESP8266 module, it works with the regular UART port on your Arduino, allowing it to connect to networks, create its own network (hot spot), or even both. This version comes with 1 MB of memory, instead of the 512 kB found on the standard ESP8266 module. However, it requires a separate programmer as there is no onboard USB.
Disclosure: This post contains affiliate links. If you click through and make a purchase, I will earn a commission, at no additional cost to you. Read my full disclosure here.