Is blog commenting still work for link building?

Yes, blog commenting still works for building links. There are numerous blogs that offer you the opportunity to build "do-follow" links through comments. I've done that, and it still works too. And, I'm talking about those blogs too which have a great page-rank as well. Just one link from them can be more valuable than 1000s of links of article directories. And, those blogs do exist. They're indeed so many of them; you can't even count.

But, there is a catch. Almost all blogs with great page-rank, and do-follow links, won't accept your comment if it's not valuable. It's necessary for you to ready their entire post and then say something valuable through your comments. You can't just say, it's great or I agree with you, and etc. You've to participate in the conversation and show through your comments that do you exactly think about it.

It will take some time to write a valuable comment - perhaps 10 minutes? But, the end result will be sweeter than the honey for SEO purposes.

 

Manual blog commenting is still absolutely relevant; even with nofollow links. This boost your relevancy score, which is very important.

For link-spam, its mostly useful for indexing.

 

I've been building the links through some blogs & other sites, but when I checked it on Ahref, we still couldnt get a link from these forum. I dont know why beacuse Ahref is very fast in crawling new backlinks

 

Yes.. But you need to do blog commenting on relevant theme. even most of the blog commenting sites give nofollow link. But it will great value to your website.