The apps i'm going to propose are available through F-Droid. The name F-Droid refers to both A.) a repository for open source android apps and to B.) an android app used to browse, download, install an manage those apps on your android device.
You might want to check out this tutorial for information on how to install F-Droid or apk-files downloaded from F-...
Depending on your intended recipient the Samsung SmartSwitch application can do everything you want.
It can back up contacts, calendars, applications and almost all other data.
It's primary use is in transferring files to a new phone, but it also has a mode to transfer data to a backup held on your MicroSD card.
In order to simply backup data in the ...
You need to enter in Chrome address bar file:///path/to/file. In case you aren't sure about the path use any file explorer that tells you the path.
In this case it is file:///storage/emulated/0/my_site/index.html
Also many file explorers including MiXplorer offer to open .html files with all supported apps (registered mime type):