Parcellite is a lightweight, tiny and free clipboard manager for Linux with a small memory footprint.
[2][3] Since development of Parcellite has slowed, a fork of it, ClipIt has appeared.
Developed by Cristian Henzel, it fixes numerous bugs and offers a better user experience, however the last commit was in 2018.
[4] Most importantly, it improves support for Unity AppIndicators,[5] UTF-8,[6] and adds support for GTK+ 3,[7] last commit[8]