See the tags any public video is using — 100% free, runs in your browser
Seeing which tags a successful video in your niche uses is a quick way to find phrasing you had not considered. This reads the public keywords that YouTube publishes in the page for search engines — no private data is involved.
Many creators leave them empty now, since YouTube gives them little weight. An empty result is common and not an error.
No. Copy the ones genuinely relevant to your video. Irrelevant tags confuse the system about what your content is.
Yes. These tags are published in the page source for search engines to read.