I found the Winx-Portable (update 17.10.2017: they are not offering this product anymore, they are offering the WiNX) on the website and I thought I have something like that. I look for the boards that I've recently bought, and I find the WeMos WiFi ESP32 Development Tool. The boards are identical. Then, I tested the available firmware and they worked on my board.
I google again to check if someone have done something with this board, and I found that Tomas C. has been also experimenting with it.
You find instructional videos on the YouTube channel of Hacker Arsenal that explain the use of the board and firmware installation. I've listed on the table, that I found interesting "Custom Captive Portals - Instructional Video".
Using putty is possible to access the data saved on the device. More info can be found on the Youtube video from Arsenal Hacker.
The maximal size of the webpage muss be under 150Kb.
The author of the code assumes no responsibility for users' decision-making and their code usage and this post.
I've just uploaded a new repository. This code compress a webpage into an html file. Images are converted to base64 and integrated together with CSS files in the html. This code can be useful for webpages on microcontrollers (or low memory devices), or a complete offline copy of a webpage etc.
where --url is the webpage that you want to download and --path is the project folder, in which all files are downloaded and the output is generated. Some optional options are available to compress the output file (remember that the maximal size of the webpage is 150Kb).
Just remember, ONLY test systems on which you have written permission. Just Google the term "hacker jailed" and you will see plenty of different examples where young teens have been sentenced to years in prison for what they thought was a "fun time." There are many free platforms where legal hacking is allowed and will help you further educate yourself.