All of our Tumblr themes have Disqus or Facebook commenting built in, and many other themes have similar customization options to set them up.
Disqus commentsYou can enable Disqus comments in your theme customization options by filling in your Disqus Shortname for your site. You will need to set up the Disqus shortname for your site from your Disqus account.
Facebook commentsIf these directions don't match what you are seeing, Facebook may have changed their setup method – and we'd love it if you could send us a message and let us know. And if at any point you feel lost, don't hesitate to get in contact!
Setting up Facebook comments requires a bit more time, but can be well worth it because, well, it's Facebook integration. First, make sure the Facebook comments toggle is enabled in your customization settings. Next, you will need to retrieve Facebook API ID, which will allow you to connect your site to a unique Facebook comments board.
Set up a Facebook App and give your app a name. You may receive an error when entering a security check, but you should be able to continue anyway. Click on the Getting started link in your new app's dashboard, choose the Website platform, and fill in your site's URL in the Tell us about your site section. After clicking the Next button, you can scroll to the top of the page and Skip the rest of the quick start guide. You will be taken back to your app's dashboard. Copy the App ID and paste it into the Facebook API ID in your Tumblr blog's customization settings.
After this, your Facebook commenting plugin should be functional.