| Project | Contact | Comment |
| SEW The System Engineer's Workbench | Dr. Kevin Bradley | I've found GTL to be really good to use, and was a perfect drop-in replacement for LEDA. |
| Visualization of huge graphs. | David Auber | I've choose your library because it's quite powerfull and natural to use. |
| Cassowary A Constraint Solving Toolkit | Greg J. Badros | Firstly, great work on GTL-- it's a nicely designed library that does what it sets out to do very well. Thanks! |
| GTool Graph-drawing tool | Kris Warkentin | I found the GTL to be a very well implemented solution for what I was trying to do (...) Thank you for a great toolkit: GTL has been very helpful to me |
| Bioinformatics: Modeling protein folding | Kjell Petersen | I was very pleased to find GTL ;^). Doing a few test examples, I found it even better due to the thorough online documentation. |