Interactively analyses Intron Retention and Alternative Splicing Events (ASE) in RNA-seq data. NxtIRF quantifies ASE events in BAM files aligned to the genome using a splice-aware aligner such as STAR. The core quantitation algorithm relies on the IRFinder/C++ engine ported via Rcpp for multi-platform compatibility. In addition, NxtIRF provides convenient pipelines for downstream analysis and publication-ready visualisation tools. Note that NxtIRFcore is now replaced by SpliceWiz in Bioconductor 3.16 onwards.