The best alternatives to Backstory for Facebook are FollowUp, Facebook Notes, and UpHabit. If these 3 options don't work for you, we've listed a few more alternatives below.
UpHabit is a contact relationship app for your important contacts that helps you build the relationships you always wish you had. Start the habit of keeping in touch with the people who matter.
I coded the first version of Keep My Friends after getting one too many "I haven't heard from you in months" messages from my friends. Everyone is busy (including me), but I found it very easy with the app reminding me to keep in touch with important people in my life and maintaining Streaks of unbroken contact in the app.
bilgge is a free service which makes you feel as if you were storing data in a real safe house. instead of saying "it uses end-to-end encryption" then asking you 8+ characters password to protect your data, it gives you power to encrypt your data by yourself in your browser.
Dnotebook is a Jupyter-like library for JavaScript environment. It allows you to create and share pages that contain live code, text and visualizations.
Private Notes for Twitter and Facebook allows to add and edit notes for any profile. Can export notes to CSV. All data is secure on your computer and is not transfered anywhere. Source code is available on Github.