Sticking with our text-based nature, Write.as/WriteFreely lets you easily group your posts together with hashtags. Add one at any point in your post, like #this, and it'll automatically be linked to a special page that shows all posts containing that hashtag.
Hashtags are also sent to the fediverse. So if your blog has federation enabled, your tagged blog posts will show up with all the other posts that people have similarly tagged when someone does a search in Mastodon, Pleroma, etc.
You can also add as many hashtags as you want to your posts, with any kind of capitalization: