MultiAzterTest is an open source NLP tool and web application which analyzes texts on over 125 measures of cohesion, language, and readability for English, Spanish and Basque. Regarding the readability assessment, it outperforms the performance of the state-of-the-art Coh-Metrix in English, Coh-Metrix-Esp in Spanish and ErreXail in Basque. It classifies three levels in English (elementary, intermediate, and advanced) and two in Spanish and Basque (simple vs complex). It is the multilingual version of AzterTest.