vidIQ

Founded in 2011 by Rob Sandie, Todd Troxell and James Cross, vidIQ began as enterprise software for managing YouTube at scale. The free Chrome extension, launched in 2013, turned it into a mass-market product by overlaying keyword scores, tags, view velocity and competitor data directly onto YouTube pages. The company pivoted towards individual creators from around 2016, built a very large YouTube channel of its own, and later acquired Video Creators and Creator Now. Its usual comparison point is TubeBuddy.

Treat the scores any tool of this kind produces as one opinion. None of them can see YouTube's actual ranking inputs.