Duolingo EO from EN versions:

Trees:
v0: 2014-09-10  ? (Beta)
v0: 2015-05-28  ? (Beta)
v1: 2016-03-25, 44 Skills (44 Different lessons)
v2: 2018-06-03, 62 Skills (62 Different lessons)
v3: ?
v4: 2019-12-29, 65 Skills (65 Different lessons)
v5: 2020-11-13, 69 Skills (69 Different lessons)

Paths:
1.0: 2022-09-10, 69 Skills (69 Different lessons) (45 Units)
1.1: 2023-09-10, 69 Skills (69 Different lessons) (45 Units)
1.2: 2024-05-01, 69 Skills (69 Different Lessons) (79 units)


tree_eo_en_v3_experiment
tree_eo_en_v4_experiment
tree_eo_en_v5_experiment
tree_eo_en_v6_experiment   (?)
tree_eo_en_v7_experiment   (?)

https://liuch.github.io/duolingo_courses_overview/
https://duolingo.fandom.com/wiki/Course_list
https://duolingodata.com/
https://duolingodata.com/oldtable.html
https://ardslot.com/duolingocrowns.html

Edited by Mat!/Ozone, 2024-05-02.