Together with the investigation of new or updated CAT procedures, it is of primary importance to ensure development of appropriate, flexible and useful CAT software. Open-source CAT algorithms have been recently proposed and are offering very promising tools for future practical CAT implementations, though yet under development. After a brief overview of available (commercial) software, I will present and compare the characteristics of some open-source R packages as CAT solutions: catR (Magis, & Raîche, 2012), catIrt (Nydick, 2013) and MAT (Choi, 2011), as well as the R-based software Firestar (Choi, 2009). A more complete description of catR will be given and (depending on time and computer constraints) a short illustrative session will be proposed. Finally, the web platform Concerto (Kosinski & Rust, 2011) will be shortly introduced. References: Choi, S. W. (2009). Firestar: Computerized adaptive testing simulation program for polytomous item response theory models. Applied Psychological Measurement, 33, 644-645. Choi, S. W. (2011). MAT: Multidimensional Adaptive Testing (MAT). R package version 0.1-3. Kosinski, M., & Rust, J. (2011). The development of Concerto: An open source online adaptive testing platform. Paper presented at the International Association for Computerized Adaptive Testing, Pacific Grove, CA. Magis, D., & Raîche, G. (2012). Random generation of response patterns under computerized adaptive testing with the R package catR. Journal of Statistical Software, 48 (8), 1-31. Nydick, S. W. (2013). catIrt: An R package for simulating IRT-based computerized adaptive tests. R package version 0.4-1.