The Universal Floristic Quality Assessment (FQA) Calculator is an open source project licensed for use under GPLv3. Get the code on GitHub.
Photo of Sisyrinchium angustifolium © Lisa Culp. Used with permission.
Freyman, W.A., L.A. Masters, and S. Packard. 2016. The Universal Floristic Quality Assessment (FQA) Calculator: an online tool for ecological assessment and monitoring. Methods in Ecology and Evolution 7(3): 380–383
Read the article here. If you publish an assessment you should also cite the FQA database used to calculate the assessment.