I have WordPress blog. And for WordPress blog there is anti spam service named Akismet. The service is from the creators of the WordPress. They seem to be good for free account too. Like most of the premium features does not exist on free accounts. But it can take care of the bots and the spam comments. So it is effective for WordPress.
So keeping the WordPress plugins, aside, which anti spam service you use on blog, be it platform like WP or Blogger or Tumblr?
I never really allow blog commenting and I removed contact form 7 from my site. I do have a contact page but it has an image of my email address people can type in if they really want to get in touch with me.
I use Akismet, just like millions of other sites. It's very handy and works very well. My latest blog uses it. I've had the blog for one year and it already stopped ten thousand spam comments from coming through. It's a wonderful plugin and if you have a WordPress blog, I strongly recommend installing it.
Even though I don't personally own or have owned a blog, I thought this is the most appropriate place to add my two cents.
A plugin known as "Stop Forum Spam" is installed on my discussion board and it has worked like a charm for me.
I use Akismet for blogs too, but I was looking for something like it for Instagram. Currently, I'm testing zen-promo.com. So far, it fights spam comments pretty well. We'll see.
There is new anti-spam like h captcha or even you could use ion icon spam to reveal images with less occurrence in the pictures or Cloudflare verification since recaptcha is an old one.