The cptutils package is set of Unix command-line programs for converting between and modifying various formats of colour gradients. Originally written to aid construction of the gradient archive cpt-city, where 7,000 colour gradients can be browsed and downloaded.
Simplified online access to the conversion facilities provided by cptutils (version 1.81). Created with the Ruby tools Sinatra, Haml and with styling provided by the Bootswatch United theme.
The code for this site is available on GitLab.