TreeIllustrator is a user-friendly application to visualize and customize phylogenetic trees. It has a broad range of functions and capabilities, such as dragging of nodes, different tree shapes, zooming and searching capabilities, and support for large trees. It acts as a solution that integrates the specificity of visualizing phylogenetic trees and the customization options of a drawing program. It also contains a simple and effective method that compares a custom tree with the Tree of Life, by detecting incongruence.