Passy is a free offline password manager with cross-platfrom synchronization.
If you’re looking for an open source and multi-platform alternative to a password manager, Passy is a good choice.

Passy’s security makes all your information encrypted with AES; It is stored offline on your device, enabling you to control and enable the highest level of protection for that data. It will put your PIN, payment card, notes, ID and identity in one place. The interface makes it easy to quickly create and add information, making setup a breeze.
Passy v1.2.0 features：

• Security – All your information is encrypted in AES and stored offline on your devices, providing highest-tier security.
• Synchronization – Share data between separate devices within seconds.
• Biometrics – Quickly unlock the app using your fingerprint.
• Multipurpose – Store passwords, payment cards, notes, id cards and identities, all in one place.
• Autofill – Quickly fill fields in apps and websites without having to open the app.

The author’s links:
https://glitterware.github.io/Passy
https://github.com/GlitterWare/Passy