That’s exactly what Ahrefs Link Intersect tool does. (Please note that the tool is available for all legacy packages with certain limitations and for new Standard, Advanced and Enterprise subscription plans).

You can add up to 10 websites to the tool and compare them with your own website. In case you want to analyze specific pages, choose the fitting mode from the right drop-down menu inline with each of the added domain or page URLs.

After pressing the “Show link opportunities” button, the list of domains that link to your competitors but don’t link to you will be seen. If needed, you can sort them out by their Domain Rating (DR) or Ahrefs Rank (read more about Ahrefs metrics here).

To check the backlinks placed on a particular domain, just click on the number as it is shown in the screenshot below.

Also, note that you can easily export the results into a handy spreadsheet. To do that, just click the “Export” button in the right corner.