YouTube URL:
How to use Thumbnail Generator? 1. Go to YouTube, search a video.
2. Copy video URL (It may be shortened with youtu.be)
3. Paste URL in the box above and hit the "OK" button.
4. Here we go! Click the "Download" button or copy URL.
Why is it better than other similar services? 1. There's no ads, analitycs or other annoying crap.
2. Just one JavaScript (thumbnail.js), nothing more.
3. Mobile-compatible interface with Bootstrap v3.3.7.
4. You can download and self-host this site!
GitLab
    GitLab