TubeBuddy is a browser extension full of small conveniences: bulk edits, tag suggestions, thumbnail A/B tests. It is cheap and it has been useful for a decade.

Spotter Studio is built around the harder problem — what should this video be? Outlier detection, title and thumbnail ideation against your own channel history, and packaging tests. If you are past the "optimize tags" stage, Spotter is the tool that moves views.