Duolingo DE from EN versions:

Trees:
v0: 2011-11-30  ? (Beta)
v1: 2012-06-19, ?
v2: ?
v3: 2015-12-15, 121 Skills (121 Different lessons)
v4-v9: ?
v10: 2020-09-10, 133 Skills (133 Different lessons)
v?: 2021-03-29, 149 Skills (149 Different lessons)
v?: 2021-04-04, 160 Skills (160 Different lessons)
v?: 2021-09-11, 178 Skills (178 Different lessons)
v?: 2022-04-01, 137 Skills (137 Different lessons)

Paths (all CEFR):
1.0: 2022-09-10, 113 Skills and 158 stories = 271 Different Lessons (114 units, CEFR B1)
2.0: 2022-12-09, 155  Skills and 187 stories = 342 Different Lessons (131 units, CEFR B1)
3.0: 2023-09-10, 150  Skills and 187 stories = 337 Different Lessons (102 units, CEFR B1)
4.0: 2024-02-02, 137 Skills and 143 stories = 280 Different Lessons (89 units, CEFR B1)
2.1: 2024-02-15, 156 Skills and 187 stories = 343 Different Lessons (178 units, CEFR B1)
2.2: 2024-05-10, 156 Skills and 187 stories = 343 Different Lessons (156 units, CEFR B1)
4.1: 2024-05-10, 137 Skills and 147 stories = 284 Different Lessons (137 units, CEFR B1)
2.3: 2024-09-20, 156 Skills, 187 stories, 143 radios, 55 adventures = 541 Different Lessons (156 units, CEFR B1)
2.4: 2025-06-20, 156 Skills, 187 stories, 575 radios, 55 adventures = 973 Different Lessons (156 units, CEFR B1)
3.0: 2025-09-10, 348 Skills, 800 stories, 628 radios, 55 adventures = 1831 Different Lessons (332 units, CEFR B1)
4.0: 2026-03-02, 630 Skills, ? stories, ? radios, 55 adventures = ? Different Lessons (630 units, CEFR B1)
5.0: 2026-03-05, 1030 Skills, 740 stories, 867 radios, 55 adventures = 2692 Different Lessons (1030 units, CEFR B2)
5.1: 2026-04-30, 1030 Skills, 1159 stories, 1267 radios, 55 adventures = 3511 Different Lessons (1030 units, CEFR B2)

Edited by Mat!/Ozone, 2026/05/16.