When comparing Clipperz vs Buttercup, the Slant community recommends Buttercup for most people. In the question“What is the best cross-platform password manager?” Buttercup is ranked 10th while Clipperz is ranked 14th.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Disposable one-time pass phrase for use on a public computer
Pro Open source
Clipperz has been around for many years as an open source project.

Pro Completely anonymous
Clipperz does not ask for any personal information, no email required, nothing.
Pro Encryption is client-side
Everything is encrypted in the browser and stored encrypted on the server.
Pro Can be run on own server
Clipperz can be run on a private server.
Pro Download local copy for backup in a pinch
Pro Can be installed with home brew
Pro Open source
There's a large base of developers who work on improving the software.
Pro Import other formats
Import passwords from other password managers including 1Password (.1pif), KeePass(.kdbx), and LastPass (.csv).
Pro Good UI
Pro It's free
As in beer.
Cons
Con Backups are up to the user
There is no service with this application, it is up to the end user to backup all data.
Con Has to be running on a server to work
Unlike other password managers such as KeePass, Clipperz can not just be simply run by executing once downloaded. It has to be setup to run on a server and then can be accessed from the necessary devices.
Con Miss 2fa
Con Miss secure filling like Keepass
