Is there a browser based IDE for Python like RStudio server for R?

Jupyterlab is due to release it's beta release in 31 Dec. 2017, it should be the most similar to RStudio server and probably the most advanced browser based IDE for Python

EDIT: According to their Github page, it is now out of beta and ready for users.

EDIT 2: According to their Github page, it is already stable for general use.