in order of completion, with the most recent trees last

• french
• english (from french)
• esperanto
• norwegian
• danish
• korean
• swedish
• german
• spanish
• portuguese
• hindi
• italian

i enjoy completing trees on duolingo to get a tourist's view of a language. finishing a decently-structured duolingo tree will take you upto slightly below A1 proficiency for a language covered by CEFR

my favourite trees on duolingo are norwegian and french, which coincidentally are also the foreign languages i'm currently the most interested in