Push OTAs to ESP8266 or ESP32 Elegantly.
https://github.com/ayushsharma82/ElegantOTA

GitHub 上还有好多
https://github.com/search?q=esp8266%2Bota
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实现乐鑫esp8266的无线OTA升级,实现远程在线升级固件
https://www.cnblogs.com/demodashi/p/9437734.html
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另一篇
基于官方SDK的ESP8266在线更新固件OTA
https://blog.csdn.net/u010694718/article/details/106092039