The Algorithm Visualization Catalog is a comprehensive collection of links to algorithm visualizations, or AVs.

AVL Tree Applet

Balanced Search Tree, AVL Tree, Search Structures

Lecture Aide Recommended
Self-study Supplement Has Potential
Standalone Not Recommended
Debugging Aide Not Recommended
Delivery Method(s)
Flash, Java Applet
Project Relationship
Stand-alone AV
Arsen Gogeshvili
University of LA Laguna
Activity Level(s)
Random data, Step control, User data
Source Code License
First Published
Last Modified


This visualization initially shows a tree with some randomly generated input and then allows user to add user defined input, such as inserting or deleting values. In addition, it has tree size control options; sound options that work seamlessly with all the animations; the animation speed control options. Textual description of each operation as well as pre and post-order traversals are provided in the visualization. Other fancy options like shape control feature and direction control features are also included. Moreover, images on command buttons help users use this tool intuitively. The visualization also shows the basic splay operation for comparison to AVL.


This visualization provides several options like user defined data, step-wise speed control, description of each operation with valuable visual effects so that a user can fit the tool to his/her preference. It also provides sound effects and animation effect, in particular, rotation signs before executing operations. This application is highly intuitive with simple and smooth animation. The descriptions after the operation has completed give an insight into what operations the Algorithm visualization went through. The write up provided by author for the algorithm in general is also insightful. Interface provides options to insert node, delete node and find nodes in predetermined or user defined dataset. It also provides good control over the speed of animation. Despite its neat design, the visualization is missing some options. The next button is missing (hence no step by step trace capability during a given insert or delete operation) which could have been an added advantage. The layout is pretty decent but it cannot support a large set of numbers on the screen. It shows the basic splay operation which is missing in many visualizations. But sadly, one has limited control the pacing of the rotation operation. One needs to control the pace of these iterations to have better understanding of the AVL concept which forms the basis of AVL. The "Options" allow one to go into "step mode" which is a big help (it pauses as it goes down/up the tree), but the actual rotation is still a single atomic animation. Further, once we press “AVL” button (apparantly this is only available in some versions), there is no getting back. One has to have a basic knowledge of the BSTs and Self Balancing trees to work with this visualization and this cannot be given to novices who have not taken any Data Structures course till now. Though a beef-up of the basic operations by providing pace control, “Previous” and “Next” Buttons, and a short text box that explains what happened in a particular iteration would make this AV a very potent and useful tool for all user groups.

Usage Notes

A number of third parties appear to have copied this AV into their own course web pages (see for example the alternate URLs above). There is a Flash version, and an older Java version, and they are slightly different in their details. The Flash version has more control options.

Important usage note: The Options menu allows the user to turn on "Step by Step" mode, which helps to get control over the pacing of the operations, and probably is preferred.


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