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Joplin
Joplin - the secure note taking and to-do app with synchronisation capabilities for Windows, macOS, Linux, Android and iOS.
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InfluxDB
Power Real-Time Data Analytics at Scale. Get real-time insights from all types of time series data with InfluxDB. Ingest, query, and analyze billions of data points in real-time with unbounded cardinality.
If you cannot pay use https://joplinapp.org/ its an open source e2e note taking app that you can use to write journals, syncs using the cloud (dropbox or google drive etc which are free) , the only problem it does not have a digital lock , but your pc and phone already have a lock so ig it should not matter
if you want to lock your notes separetly use dropbox/ google drive to store the notes in a cryptomator vault , this is an open source encrypted vault that will only open on passwords and is specifically designed to be used with cloud storage ( although you can use it normally too to store sensitive material on your pc and phone) the phone app is paid https://cryptomator.org/