Entirely free, customizable, and great if you need to design custom PCBs around the raw ESP32 module instead of a bulky development board.
if (WIFI_ENABLED) WiFi.begin("SSID", "PASS"); // ... Real logic else Serial.println("SIM MODE: Skipping WiFi"); // Mock HTTP responses here esp32 library proteus best
Open your coding environment (e.g., Arduino IDE) and write your sketch or load an example. Entirely free, customizable, and great if you need