How to transfer files over WiFi without a hotspot?
Connect your computer with virtual hotspot created by Android device.
Install any FTP Server app on Android device. It'll NOT give you IP of device for sure. :)
In your computer, find IP of Default Gateway of Wi-Fi network of Step 1 (In Windows, you can use ipconfig cmd command). Its the IP of your device.
Use any FTP Client software on computer. Use ftp://IP:Port (Port is generally configurable in FTP server app). Enter username &amp; password configured in FTP Server app. Done!