Duolingo EL from EN versions:

Trees:
v0: 2015-02-19  ? (Beta)
v0: 2016-08-30, ? (Beta)
v1: 2017-02-12, 74 Skills (74 Different Lessons)
v2: 2020-12-29, 95 Skills (95 Different Lessons)
v3-v8: ?
v9: 2021-10-26, 102 Skills (102 Different Lessons)


Paths:
1.0: 2022-09-10, 95 Skills (95 Different Lessons) (61 units)
1.1: 2023-09-10, 95 Skills (95 Different Lessons) (62 units)
1.2: 2024-05-01, 95 Skills (95 Different Lessons) (108 units)

tree_el_en_v1_experiment
tree_el_en_v2_experiment
tree_el_en_v3_experiment
tree_el_en_v4_experiment
tree_el_en_v5_experiment
tree_el_en_v8_new
tree_el_en_v9_existing

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.