Use labelled bracket notation. This app will build the tree as you type and will attempt to close any brackets that you may be missing. Save the image to your computer by right-clicking on it and selecting "Save image as". For more information, including on how to draw movement lines, visit the wiki.

Examples

[NP^ Alice]
[NP [N Alice] and [N Bob]]
[S[NP[N Alice]][VP[V is][NP[N'[N a student][PP^ of physics
[S [X_a Movement] [Y example <a>]]