Duolingo NB from EN versions:

Trees:
v0: 2015-01-20  ? (Beta)
v0: 2015-05-21  ? (Beta)
v1-v5: ?
v6: 2015-08-11, 117 Skills (117 Different lessons)
v7: ?
v8: 2018-09-20, 172 Skills (172 Different lessons)

Paths:
1.0: 2022-09-10, 172 Skills (172 Different lessons) (111 Units)
2.0: 2022-11-10, 246 Skills (246 Different lessons) (159 Units)
2.1: 2023-09-10, 246 Skills (246 Different lessons) (161 Units)
2.2: 2024-05-01, 246 Skills (246 Different Lessons) (281 units)


tree_no-BO_en_v3_experiment
tree_no-BO_en_v4_experiment
tree_no-BO_en_v5_experiment
tree_no-BO_en_v7_experiment
tree_no-BO_en_v8_experiment
tree_no-BO_en_v8_launch_new

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.