John Mueller said that you should be consistent in the URL version on your website. If the URLs on your website work with and without a slash, you should use only one version.
The best solution is to be consistent and only use one version of a URL. Link to that version, redirect to it, use it in sitemaps, use it for rel-canonical, etc.— ? John ? (@JohnMu) July 11, 2019
How to check if your web pages are linked consistently
The website audit tool in SEOprofiler checks if you link consistently to your web pages. Just sort the URLs in the audit tool and you will quickly see duplicate URLs.
The audit tool also checks if you mix links to HTTP/HTTPS pages, if you link to inaccessible pages, if the HTTP status codes are correct, and much more: