For SEO purposes, you always want to make sure that the canonical url always is consistent with the url. So if you allow both a URL with and without the trailing slash, you need to make sure that your canonical is the same for both.
For SEO purposes, you always want to make sure that the canonical url always is consistent with the url. So if you allow both a URL with and without the trailing slash, you need to make sure that your canonical is the same for both.