iOS/macOS/Win/Android Codebook, https://www.zetetic.net/codebook/

  - no subscription
  - open-source encryption (SQLCipher)
  - device-to-device encrypted sync via ethernet/wifi, dropbox, google drive
  - indie US developer, lineage to 1998 STRIP on PalmPilot
  - TOTP 2FA authenticator
  - sync encrypted notes/images

1999, http://www.cnn.com/TECH/computing/9911/30/palm.tools.idg/

> Secure Tool for Recalling Important Passwords (STRIP). STRIP uses heavy-duty, 128-bit triple-Data Encryption Standard to store information, and that means any information -- credit-card numbers, Web site accounts and voice-mail access codes. STRIP (Zetetic Enterprises, free) is also a great tool for IT managers who administer distributed environments. It can random-generate complex passwords and allows account information to be beamed between Palms, so the IT staff can stay up-to-date.