Review on 📡 Makerfocus ESP8266 ESP-01S WiFi Serial Transceiver Module (4pcs) with 1MB Flash for Arduino - Enhanced Connectivity and Storage by Tamara Allen

I love these things. You can use 4 I/O pins. GPIO-0 and GPIO-2 are labeled and ready to use, but you can use GPIO-1 and GPIO-3 (TX/RX) if you prefer. I replaced the SPI flash chip with a W25Q32FVSIG which increases the flash by 1MB. Memory up to 4MB (32MB) like most regular ESP8266 modules. This made it easier to use OTA updates and freed up space for SPIFFS files. I used a heat gun to remove the old chip, apply some flux, install the new chip and heat it until it starts to flow. All 4 worked the first time.