iTOL

iTOL stands for Interactive Tree Of Life and is a web-based platform for visualizing, annotating, and exploring phylogenetic trees. It supports a wide range of tree formats and data attachments, allowing users to upload trees (for example in Newick or Nexus formats) along with associated metadata for visualization.

Key features include multiple layout options (rectangular, circular, or cladogram), interactive navigation (zoom, pan, search), and extensive customization of labels and color schemes. Data visualization options include color strips, charts, and heat maps attached to leaves or branches to reflect metadata such as taxonomy, geography, or phenotypic traits. Users can add textual annotations and export results as high-quality images or interactive web pages. Sessions can be saved and shared via links.

iTOL is widely used by researchers in evolutionary biology, microbiology, and bioinformatics to interpret and present phylogenies in publications and presentations. The platform supports both exploratory analysis and the production of publication-ready figures, with an emphasis on user-friendly, interactive visualization and flexible customization.

The service is hosted online and maintained by developers who provide documentation and, on request, programmatic access via an API. iTOL remains a popular tool in the phylogenetics community for integrating evolutionary trees with diverse metadata and producing versatile visual outputs.