R package JoSAE: Unit-Level and Area-Level Small Area Estimation. Implementation of some unit and area level EBLUP estimators as well as the estimators of their MSE also under heteroscedasticity. The package further documents the publications Breidenbach and Astrup (2012) <doi:10.1007/s10342-012-0596-7>, Breidenbach et al. (2016) <doi:10.1016/j.rse.2015.07.026> and Breidenbach et al. (2018 in press). The vignette further explains the use of the implemented functions.