The Great Lakes Commission (GLC) invites proposals from qualified applicants to provide software engineering services to develop updates and enhancements to an existing web-crawling software system. The existing system - Great Lakes Detector of Invasive Aquatics in Trade (GLDIATR) - searches the web to identify websites offering invasive species for sale. These services will be provided as part of an overall project for which the GLC has received funding from the U.S. Environmental Protection Agency's Great Lakes Restoration Initiative program (glri.us). The requested services are expected to be completed by January 31, 2017 with maintenance as needed through January 31, 2018.