TreeLine is used to organize and store text data in a tree structure. It is well suited to keeping track of many different types of information. Each node of the tree can contain several defined fields, forming a mini-database. The format of each node can be defined, and the output can be shown on the screen, printed, or exported to HTML. The tree structure is navigated and edited in the left pane of the window, while various views of the child data are shown and editable in the right pane. The data is stored in XML text files. TreeLine is based on the PyQt library.