Duolingo CS from EN versions:

Trees:
v0: 2015-07-06  ? (Beta)
v1: 2017-09-05  ? (Beta)
v2: 2018-05-29 84 Skills (84 Different lessons)
v3: 2020-09-03, 88 Skills (88 Different lessons)

Paths:
1.0: 2022-09-10, 88 Skills (88 Different lessons) (57 Units)
2.0: 2022-09-10, 84 Skills (84 Different lessons) (54 Units)
1.1: 2023-09-10, 88 Skills (88 Different lessons) (57 Units)
2.1: 2023-09-10, 84 Skills (84 Different lessons) (55 Units)
1.2: 2024-05-01, 84 Skills (84 Different Lessons) (96 units)
2.2: 2024-05-02, 88 Skills (88 Different Lessons) (100 units)

tree_cs_en_v1_experiment
tree_cs_en_v2_experiment
tree_cs_en_v3_experiment_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, 2024-05-04.