In Ontario, Canada, you can camp for free on Crown land, which makes up about 87% of the province. Crown land offers dispersed, backcountry camping with no facilities, so you'll need to be prepared and practice Leave No Trace principles. Some popular areas for free camping in Ontario include:
Keep in mind that you'll need a Crown land Camping Permit if you're a non-resident of Canada. You can find more information about Crown land camping and regulations on the Ontario government's website.