Can be used with any game that uses only a single save file.

Confirmed working for:
Dark Souls
Dark Souls 2
Dark Souls 3
Elden Ring

Download: https://github.com/omgftw/DarkSoulsSaveManager/releases

Get node: https://nodejs.org
Run "npm install" from command line in the root directory (The directory containing "package.json")
Run "npm install -g electron"
Run "electron main.js" from command line in the root directory
Open the project in your favorite editor/IDE and edit the files in the "app" folder
After making changes hit "Ctrl+R" or select "View -> Reload" From the menu

Get node: https://nodejs.org
Get InnoSetup Run "npm install" from command line in the root directory (The directory containing "package.json")
Run "gulp build"
Run the installer.iss file using InnoSetup
The installer can be found in the "Output" directory