Download Vortex

This page provides access to the Vortex Population Viability Analysis software produced by Bob Lacy (Conservation, Education, and Training, Chicago Zoological Society, Brookfield, Illinois, USA).

Vortex is copyrighted, but is distributed without cost for the purpose of furthering conservation and research. Individuals and not-for-profit organizations are hereby given licenses for using Vortex in research and conservation.

Distribution of Vortex is restricted to:

distribution by the Chicago Zoological Society;
distribution by the IUCN/SSC Conservation Breeding Specialist Group;
downloading the program from the Internet by individuals and not-for-profit organizations for their own research and conservation applications;
redistribution without charge of the unmodified executable program for the purposes described above.

Redistribution of Vortex, in whole or in part, by any for-profit organization or for any profit-making purposes, is expressly forbidden


A Note About Cost

Vortex is provided free of charge because of the commitment of the Chicago Zoological Society to making it widely available to further biodiversity conservation. Similarly, the manual, developed by CBSG, is provided for downloading because CBSG cares about saving species and their habitats. However, the initial development and continuing improvement of the software and manual do represent a significant commitment by these conservation organizations. The rate at which improvements can be made is determined by the resources available to support that work.

If your budget allows it, please consider making a donation to support the further development of Vortex. If you find the software to be especially valuable to you, consider donating perhaps US$100 (a wild guess about the investment of resources per user that have gone into Vortex), or more or less as you feel is appropriate. If you find the manual to be especially helpful, consider donating to CBSG. As a side benefit to US tax-payers, donations to either the Chicago Zoological Society or CBSG are tax-deductible.

Download Vortex 10 - current version released 28 January 2015

Download Vortex 10 manual - about 5 MB

Vortex installation instructions - click here.

Vortex Users Listserv

To subscribe to the Vortex users Listserv (email discussion group), go to VORTEX Listserv.
If you think you have discovered a bug in Vortex, please go to VORTEX Bug Report.
If you experience problems using Vortex, we encourage you to check the manual first, but if you still have questions, you may email us at

Vortex is copyrighted but not copy protected. Individuals and not-for-profit organizations can make copies of Vortex for use in their own research and conservation efforts or for others who have similar need for it. You cannot legally sell the program to others or distribute it as your own work.

Good luck in your use of Vortex and all of your conservation efforts!

Other software programs by Bob Lacy are available on his website.


Back to Vortex page.