[Ottawa] Ottawa Public Health: COVID-19 Testing and Care Information — Ottawa residents can access free rapid antigen test (RAT) kits from various locations across the city, including the Ottawa Public Library and Neighbourhood Health and Wellness Hubs. You can use a map to find a location close to you.
[Toronto] Toronto: COVID-19: Testing — Find free rapid antigen tests near you. Free rapid antigen tests are available at all Toronto Public Library branches, City Hall, and a number of other locations in Toronto.
[Canada] PPE Supply Canada — sells the Flowflex rapid tests.
[European Union] maskwholesale.eu — This shop is based in Germany, but it can ship rapid tests and respirators to international addresses. There is a good selection of rapid tests and respirators (e.g. the Flowflex rapid tests).