Tasmota is described as 'Alternative firmware for ESP8266 with easy configuration using webUI, OTA updates, automation using timers or rules, expandability and entirely local control over MQTT, HTTP, Serial or KNX' and is a IoT Platform in the network & admin category. There are three alternatives to Tasmota for Self-Hosted, Arduino IDE and YunoHost. The best Tasmota alternative is ESPHome, which is both free and Open Source. Other great apps like Tasmota are OpenMQTTGateway and ESPEasy.
ESPHome is a system to control your ESP8266/ESP32 by simple yet powerful configuration files and control them remotely through Home Automation systems.
OpenMQTTGateway project goal is to concentrate in one firmware different technologies and protocols, hiding the different technologies singularity behind a simple & wide spread communication protocol.
The ESP Easy firmware can be used to turn the ESP module into an easy multifunction sensor device for Home Automation solutions like Domoticz.
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different approach but both are powerful firmware, simple to use, for interfacing iot devices