I think https://www.crunchbase.com/ is an absoulte gem!

Brandfetch.com

Finding high DR (Domain Rating) backlinks for free can be quite challenging, but focusing on creating high-quality content and engaging with communities in your niche can naturally attract them. Additionally, guest blogging on reputable sites and leveraging social media platforms can significantly increase your chances of securing these valuable backlinks.

First: DR is a bad metric for comparing backlinks. Google has PageRank so the strength of a backlink is considered on page level Then: it depends on your niche, but libhunt.com is quite a strong backlink. Finally: I have created a guide with the best free backlinks putting your own DR above 20: https://backl.io/directory

https://rankingraccoon.com/ is a platform where you can browse verified, manually handpicked websites in your niche and message site admins directly