First let me refresh your memory. Next to the NodeMCU and Wemos D1 Mini boards there is still the ESP-01 board available. It is not as popular as the other versions because it only has 2 I/O ports and no USB interface. However for building simple sensors like a thermometer or movement detector etc it is excellent. It uses not a lot power because the lack of USB chips etc.
Long time ago, November 2015 to be exact, I wrote a story about building your own ESP-01 programmer. You can re read that story here.
http://lucstechblog.blogspot.com/2015/11/esp8266-01-programming-board.html
It is bulky and needs an FTDI (USB to serial adapter) but does the job flawlessly.
Now there is an alternative. And it is much cheaper as my DIY version. You do not need a separate FTDI, nor a piece of PCB, buttons etc. It is all inclusive, and a lot less bulky.
The trick is on this side.
The button puts the module in programming mode when slided to the ESP header. When the button is slided towards the USB connector the module is in communication mode. That's all. I use it frequent lately on a Windows 10 computer system without any problems.
The only flaw in my opinion is that it lacks a reset button. So to reset it you have to cut the power supply. The good part is it's small size and has a cheap price.
So when you are starting with using ESP-01 modules and want a cheap programmer this is a good solution. Just beware that you buy the one with the switch cause there are a lot of these look-alikes without the switch and those are just usable for communication and not for programming.
For those who need a quick reminder I also give you here the link to my story about the programming software for the ESP-01. Only needed if you are going to use ESP-Basic or Lua.
http://lucstechblog.blogspot.com/2015/11/flashing-esp8266.html
Till next time.
Have Fun
Luc