NimbleCal is built around end-to-end encryption.
What this means
End-to-end encryption means your calendar content is encrypted on your device before it is synced/stored, so NimbleCal cannot read it during normal sync.
Invites are different
Email invites are a separate delivery flow. NimbleCal stores and sends a plaintext invite summary with the event title, start/end time, timezone, organizer name/email, and any event location or description.
Email invite details are accessible to anyone with the invite link. Keep invite links private.
See: Invite participants
What might not be encrypted
Some minimal metadata may be stored unencrypted to support features like reminders.
For the detailed, canonical explanation, see: