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SponsorBlock:

SponsorBlock is an open-source crowdsourced browser extension and open API for skipping sponsor segments in YouTube videos. Users submit when a sponsor happens from the extension, and the extension automatically skips sponsors it knows about using a privacy preserving query system. It also supports skipping other categories, such as intros, outros and reminders to subscribe, and skipping to the point with highlight.

It’s available for every single imaginable platform, including the most popular web browsers and TV operating systems (e.g. Android TV).

You can also use it indirectly via Grayjay or SmartTube.