The best alternatives to AirNotes are Wave X, Knoto, and Postpone Pixel. If these 3 options don't work for you, we've listed a few more alternatives below.
What do you think of AirNotes?
Agree.com— Free e-signature for everyone with invoicing and payments!
Pixus is a collaborative photo organizer that respects your privacy. It encrypts your photos before they leave your device and stores them in the storage of your choice. Pixus is open source.
A privacy-focused, full resolution photo sharing app for groups. Consolidates your shared and personal albums into one, enabling you to collaborate on an album together whilst still being personalised. Cloud-synced and end-to-end encrypted for total privacy.