http://www.inaturalist.org 

This website is a global database and mapping system aimed at recording all biological observations. To report an invasive species location on this site, you will need to apply for a free user account. Observations are ranked by the accuracy and amount of information associated with them, and users can help identify or confirm species. There is also a map where you can query and view occurrences of species that have been reported to the site, and a tools such as a journal and list creator. Many organizations have also established projects that users can add their observations to. A mobile app is also available and highly recommended.