What link building tools do you use?

[Kane]

Link building is very important for search engine optimization. Without building links, it is quite impossible to rank high on search engines. There are a lot of tools to build links, what are your favorite link building tools?
Some of my favorite link builkding tools include BuzzSumo, BuzzStream, Backlink Gap, Pitchbox, Link Building Tool, etc.
Have you used any of these tools mentioned above?