yaota8266 is yet another bootloader/over-the-air (OTA) update solution for ESP8266 WiFi SoC. Unlike many other solutions, yaota8266 does not require reserving FlashROM space of 2x the size of the firmware. Instead, it updates the firmware in-place. Of course, this means that if an OTA update fails, there's no previous firmware to fallback to. On the other hand, if OTA update fails, you likely will repeat it again, until it succeeds. So, for many usecases the process of OTA update will be the same - a user will just repeat it until it succeeds, regardless whether there's a fallback firmware or not. yaota8266 is written with big firmwares and small flash sizes in mind. For example, it allows to have an OTA for full-fledged MicroPython (firmware sizes of 512+KB) on 1MB flash devices, and still have a small, but a filesystem.