ESP8266 OTA flash tool

We had the requirement to enable easy ESP8266 OTA updates standalone - without PIO or Python installed and without use of PIO remote (no wan access): Therefore we developed a small tool.
The tool is freeware - may anyone else like to flash the bin files to an ESP that way.
Download at http://1st.bitbumper.de/ota-firmware-update-tool-for-esp8266/.
At the moment the tool do not support the auth command - cause the way we use it we controll the access on ESP side. If anyone need the auth handshake just tell and we will implement.

What precautions do I need to take regarding the ESP8266 unit itself?

see the developers doc at BitBumper: You can use any ESP, use PIO to develop: This brings all you need. If you are able to do an OTA update with PIO you can use the tool as well.