Modern evolution of Esperanto

The international auxiliary language Esperanto has been mostly stable since its creation, especially as compared to other constructed languages. This is due to the Declaration of Boulogne in 1905, which made the early works of Zamenhof binding; most attempts to change the language have been therefore seen as distinct language projects (so-called Esperantidos), and for the most part the Esperanto community has ignored them.

Source: Wikipedia — Modern evolution of Esperanto (CC BY-SA 4.0)