Hello, I'm Oscar from Alvento Ltd, the maker of NullKey.

NullKey keeps private notes, documents and photos together in an encrypted vault on your Android phone. There is no account, no ads and no developer server. The vault works offline; the optional purchase is handled by Google Play.

You can keep 30 photos, files and notes free in total. An optional one-time purchase removes the item limit. Google Play shows the price for your country. No subscription. Existing items, editing, export, backup and restore stay free.

The gallery shows the app with sample data. Photos and notes open inside NullKey. Other files, including PDFs and videos, open through a readable export outside the vault's protection. You need to keep your own encrypted backup and recovery key. A lost phone needs a backup, not just a recovery key.

I'd welcome written questions about whether that workflow fits what you need. I will answer here in writing.

App details: https://alvento.uk/nullkey/

Google Play: https://play.google.com/store/apps/details?id=uk.alvento.nullkeyapp

Your files. Your keys. Not ours.