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Aegis Authenticator is a free open-source app for generating and storing 2FA tokens (HOTP/TOTP) with encryption, biometric unlock, group organization, and automatic backups.

Safe — a password manager with data storage in user's cloud storage (iCloud, Google Drive, Dropbox, etc.), supports passkeys, built-in 2FA and cross-device synchronization, but has synchronization stability issues and restrictive licensing policy.

Telegram is a simple, fast, and secure messaging app that can be used simultaneously on multiple devices.

Password manager with offline-first operation, AES-256 encryption, optional cloud synchronization, and Passkey support.

Obsidian is an app for creating a knowledge base from local Markdown files with graph visualization and plugins; on mobile platforms it suffers from numerous bugs with interactivity and text input.

KeePassDX is a local password manager for Android supporting KeePass formats, biometric authentication and TOTP/HOTP, without requiring internet connection or cloud synchronization.

An inventory app for collections (movies, books, games, etc.) with barcode scanning, cloud synchronization across devices, and a database of millions of items, but with limitations on free items and basic database functionality.

E-book reader supporting multiple formats (EPUB, PDF, DJVU, FB2, MOBI, comics, audiobooks) with cloud synchronization across devices and integration with cloud services and OPDS catalogs, but with performance issues and lack of active support.