Cryptpad:

• Full-on google docs / office365 / libreoffice type replacement with collaboration.
• E2EE
• The complexity means it doesn't work well on mobile, takes a while to load on a slow connection, more frequent bugs. (3.5 MiB page transfer)
• Self-hosting is complicated.

Etherpad:

• A competent collaborative rich-text editor. Doesn't do spreadsheets or presentations or [...].
• Not E2EE (you need to trust that the server a bit more).
• Lightweight, works on slower connections, works alright on mobile. (1.7 MiB page transfer)
• Self-hosting quite simple.

PrivateBin:

• Super-simple plain-text/markdown pastebin. No editing possible once saved.
• E2EE
• Very small. Works fine on slow connections and mobile. (0.2 MiB page transfer)
• Self-hosting very simple.

What do you want this for? If the idea isn't multi-user collaboration, why not just use local tools instead of a web app?