We describe rrecsys, an open source extension package in R for rapid prototyping and intuitive assessment of recommender system algorithms. Due to its wide variety of implemented packages and functionalities, R language represents a popular choice for many tasks in Data Analysis. This package replicates the most popular collaborative filtering algorithms for rating and binary data and we compare results with the Java-based LensKit implementation for the purpose of benchmarking the implementation. Users can easily tune available implementations or develop their own algorithms and assess them according to the standard methodology for offline evaluation. Thus the rrecsys package represents an easily accessible environment for piloting recommender algorithms on diverse datasets.