W-IQ-TREE is an intuitive and user-friendly web interface and server for IQ-TREE, a powerful phylogenetic software designed for maximum likelihood analysis. It supports various sequence types (DNA, protein, codon, binary, and morphology) and a wide range of evolutionary models, including mixture and partition models. Key features of W-IQ-TREE include fast model selection, partition scheme finding, efficient tree reconstruction, ultrafast bootstrapping, branch tests, and tree topology tests. All computations are performed on a dedicated computer cluster, and results are accessible via URL or email. The software is freely available at http://iqtree.cibiv.unicv.ac.at and does not require login. Since its launch in April 2014, W-IQ-TREE has seen steady growth in user numbers and job submissions, attributed to its user-friendly features. The article also provides detailed descriptions of input data formats, model selection procedures, search parameters, branch support analysis, tree topology evaluation, and result outputs.W-IQ-TREE is an intuitive and user-friendly web interface and server for IQ-TREE, a powerful phylogenetic software designed for maximum likelihood analysis. It supports various sequence types (DNA, protein, codon, binary, and morphology) and a wide range of evolutionary models, including mixture and partition models. Key features of W-IQ-TREE include fast model selection, partition scheme finding, efficient tree reconstruction, ultrafast bootstrapping, branch tests, and tree topology tests. All computations are performed on a dedicated computer cluster, and results are accessible via URL or email. The software is freely available at http://iqtree.cibiv.unicv.ac.at and does not require login. Since its launch in April 2014, W-IQ-TREE has seen steady growth in user numbers and job submissions, attributed to its user-friendly features. The article also provides detailed descriptions of input data formats, model selection procedures, search parameters, branch support analysis, tree topology evaluation, and result outputs.