Where the hidden tags come from
When creators upload a video, YouTube Studio offers a Tags field. Those keywords do not appear anywhere on the watch page, but YouTube's official Data API returns them with the rest of a public video's details. This tool asks that API about the video you paste, then lays out the response: title, description, channel, publish date, view, like and comment counts, and the tag list. It reads only what a video's owner has already made public to the API, and it works with normal video links, Shorts and live links.
Private and deleted videos return nothing. A public video with an empty tag list is common and not an error, since plenty of successful channels never fill the field in.
How much tags matter, according to YouTube
YouTube's own help page answers this directly: tags "play a minimal role" in discovery, and are mainly useful when a video's subject is commonly misspelled. The same page says the title, thumbnail and description are the more important metadata. Any tool or course promising a ranking jump from better tags is promising more than YouTube says they can deliver.
So the value of seeing someone else's tags is research. They show which phrases a creator had in mind while publishing: the alternate spellings, the product names, the terms that did not fit in the title. If you are planning a video on a topic, reading the tags on five successful ones gives you a vocabulary list in a couple of minutes. Those terms are far more useful in your script, title and description than in your own Tags field.
Tags and hashtags are separate systems
People mix these up constantly, and the tool lists them separately because they behave differently.
- Tags are entered in YouTube Studio, are invisible to viewers and can contain spaces, such as "no knead bread".
- Hashtags are typed into the title or description with a # sign. Viewers see them as links, and clicking one opens a page of other videos using it. They cannot contain spaces.
- Keywords are not a field at all. The word just refers to the terms people search for, wherever you happen to use them.
The section headed "Hashtags in the description" is pulled from the description text, with duplicates removed. The #Hashtags copy button does something different: it converts the video's tags into hashtag form by stripping spaces and punctuation, so "no knead bread" becomes #nokneadbread. That output is a convenience, and a tag that reads naturally as a phrase can be hard to read when joined up.
Counting against the 500-character limit
YouTube allows 500 characters of tags per video. The figure next to the tag list is the tags joined by commas, with the commas counted. Three tags work out like this:
sourdough starter 17
bread recipe 12
no knead bread 14
two commas 2
total 45 of 500YouTube Studio's own counter can come out slightly higher, because tags containing spaces may be counted as if they were wrapped in quotes. If you are close to the limit, trust what Studio shows when you paste them in. The same panel also reports the length of the title against its limit of 100 characters and the description against its limit of 5,000.
What the green tags tell you
A tag shown in green also appears in the video's title. Since the title carries far more weight than the tag field, a green tag points to the phrase the creator most wanted to rank for, and the count beneath the list tells you how many tags overlap. Tags that stay red are the secondary ideas, and those are often where the useful research is.
The check looks for the tag's letters anywhere in the title, ignoring case. A short tag like "art" will show green on a title containing "smart", so glance at the title before reading much into a short one.
Using a competitor's list responsibly
Copying a full list across to your own video is the least useful thing you can do with it. Tags that describe someone else's content will not describe yours, and YouTube's spam policies prohibit misleading metadata, including tags and descriptions that are unrelated to the video or stuffed with excessive keywords. Other channels' names are a common example, and they often appear in tag lists because creators copied them from each other.
A better routine is to run three to five top videos on your topic, write down the terms that recur across them, keep only those that genuinely describe what you made, and put the most important one in your title and the first lines of your description. Add a few misspellings to your tag field if your subject is often mistyped, because that is the use YouTube itself recommends.