Duolingo JA from EN versions:

Trees:
v0: 2017-02-02  ? (Beta)
v0: 2017-10-11  ? (Beta)
v1: 2018-02-12, 40 Skills (40 Different lessons)
v?: 2018-05-17, 66 Skills (66 Different lessons)
v?: 2018-12-05, 87 Skills (57 Different lessons)
v?: 2019-07-29, 92 Skills (92 Different lessons)
v?: 2019-10-10, 121 Skills (121 Different lessons)
v4: 2020-01-09, 131 Skills (131 Different lessons)
v?: 2020-10-10, 142 Skills (142 Different lessons)
v15: 2020-11-01, 136 Skills (136 Different lessons)
v16: 2021-06-09, 169 Skills (169 Different lessons)

Paths:
1.0: 2022-09-10, 131 Skills (131 Different lessons) (90 units)
1.1: 2022-11-01, 131 Skills and 30 Stories = 161 Different Lessons (90 units)
2.0: 2023-02-20, 169 Skills (169 Different lessons) (125 units)
2.1: 2023-09-01, 169 Skills and 30 Stories = 199 Different Lessons (125 units)
3.0: 2023-09-10, 193 Skills and 30 Stories = 223 Different Lessons (121 units)

CEFR:
1.0: 2023-10-10, 193 " and 30 stories = 223 Different Lessons (212 units, CEFR A1)
1.1: 2023-10-10, 283 skills and 30 stories = 313 Different Lessons (212 units, CEFR A1)
1.2: 2023-12-15, 283 skills and 30 stories = 313 Different Lessons (143 units, CEFR A1)
1.3: 2024-05-01, 283 Skills and CC stories = CC Different Lessons (CC units, CEFR A1)
2.0: 2024-04-22, Experimental, ?  (CEFR A2)


tree_ja_en_v3_experiment
tree_ja_en_v4_experiment
tree_ja_en_v5_experiment
tree_ja_en_v6_experiment
tree_ja_en_v7_experiment
tree_ja_en_v8_experiment
tree_ja_en_v9_experiment
tree_ja_en_v10_experiment
tree_ja_en_v11_experiment
tree_ja_en_v12_experiment
tree_ja_en_v13_experiment
tree_ja_en_v14_experiment
tree_ja_en_v15_experiment
tree_ja_en_v16_experiment
tree_ja_en_a1_1_1_existing
tree_ja_en_a1_1_1_android_new
tree_ja_en_a1_1_1_ios_new
tree_ja_en_a1_1_1_web_new
tree_ja_en_a1_1_2_a1_2_existing
tree_ja_en_a1_1_2_a1_2_new
tree_ja_en_bonsai_ios_new
tree_ja_en_bonsai_web_new
tree_ja_en_a1_2_a2_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.