Free video downloader tool with 40 million visits per month

Recently I came across this super simple tool to download videos from Instagram. It has nearly 40 million visits per month, that's insane, to be honest. I'm wondering, how is it possible to gain so much traffic for simple online tools, e.g. online calculators, video downloaders, etc?
I see that website has a blog, but it has only 8 posts and I doubt that all the traffic is coming from them.

SEO experts, do you have any ideas on this?