Ranked in these QuestionsQuestion Ranking
Pro Free, open source and cross-platform
Trelby is available absolutely free for Windows and Linux with source code available on GitHub.
Pro Final Draft compatible
Can import and export .fdx files.
Pro Has a character name database
A character name database with 200k+ names from various countries is built into Trelby.
Pro Can highlight differences between different versions of a script
Con No longer maintained
Right now in 2018, most recent updates are from three or more years ago. This creates problems installing the .deb releases on certain linux distros, and means it probably wont be getting long term support anymore.
Con Can't use bold, italic, underline
Con English only
Trelby supports the ISO-8859-1 character set, any characters that are outside of that set are not supported.
Con No online collaboration capabilities
Con Lacks revision tracking
Con No OSX version
Trelby is only available on Windows and Linux.