Duolingo EN from AR versions:

Tree Versions:
v0: 2014-05-10, ? (beta)
v1: 2015-08-10, 31 Skills = 31 Different Lessons
v2: 2018?, 58 Skills = 58 Different Lessons
v3: 2019?, 61 Skills = 61 Different Lessons

Path Versions:
1.0: 2022-11-10, 40 units (61 Different Lessons) (NOT CEFR aligned)
2.0: 2023-01-11, 61 units (58 Different Lessons) (NOT CEFR aligned)
1.1: 2023-09-10, 39 units (61 Different Lessons) (NOT CEFR aligned)
2.1: 2023-10-05, 69 units (58 Different Lessons) (NOT CEFR aligned)
3.0: 2023-12-02, 163 units (246 Different Lessons) (CEFR B2)
3.1: 2023-01-10, 163 units (246 Different Lessons and 12 stories = 257 Different Lessons) (CEFR B2)
1.2: 2024-03-12, 39 units (61 skills and 12 stories = 73 Different Lessons) (NOT CEFR aligned)
1.3: 2024-04-29, 39 units (61 Different Lessons) (NOT CEFR aligned)
2.2: 2024-05-10, 61 units (61 Different Lessons) (NOT CEFR aligned)
3.2: 2024-05-10, 236 units (246 Different Lessons) (CEFR B2)
4.0: 2024-12-20, 305 units (305 Different Lessons) (CEFR B2)

JSON data and links:

android_56_bundle_en_ar_placement_test
path_stories_en_ar_test
stories_en_ar_test
stories_en_ar_testing
tree_en_ar_b1_b2_ch4_AMEE
tree_en_ar_b1_b2_ch4_AMEE_v2_new
tree_en_ar_v2_experiment
tree_en_ar_v3_experiment
tree_en_ar_v4_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, 2025 03 15.