The YouTube Data V3 API is completely "free". You have a default quota limit (quite limited even for small projects) and you can see here how it is consumed based on how you make use of the API.
Answer from E-Berry on Stack OverflowVideos
What is the YouTube Data API pricing?
What is the cost of using the YouTube API?
Is the YouTube API free for developers?
I've been playing with YT API for a few hours, and mainly practicing searching for videos..
and for each video I'm checking the snippet data (status and stuff)
I left the search params mostly default so I'm getting around 10 results per page only therefore I assume for every time I run my code I hit the API with 11 requests
Again, 1 for listing of videos (search)
$apiUrl = "https://www.googleapis.com/youtube/v3/search?part=snippet&maxResults={$maxResults}&q=" . urlencode($searchTerm) . "&key={$apiKey}&isVideoEmbeddable=true";
and 10 for checking each video's status
$apiUrl = "https://www.googleapis.com/youtube/v3/videos?part=status&id={$videoId}&key={$apiKey}";
Now I estimate I've run my code definitely less than 100x so I'm baffled why I hit the 10K requests per day limit!
confused
I've currently got 100k quota (received an increase). But I can't really scale it at the moment because costs are high for quota (e.g posting a comment is 50 unitsx20 comments day = 100 users). I'd like to know if anyone has received any quota beyond this, thanks!
https://developers.google.com/youtube/v3/determine_quota_cost