What you get
YouTube stores each video's thumbnail at several fixed sizes on its own image servers. This tool builds the links to those files from the video ID — the images come straight from YouTube, nothing is re-hosted or altered here. Older or low-resolution uploads may not have the max-resolution file; the smaller sizes always exist.
Using thumbnails fairly
A thumbnail belongs to the creator who made it. Download your own to reuse across platforms, or someone else's for reference, commentary or study — not to pass off as yours.
Questions
Does this work with Shorts and live streams?
Yes — any link that contains a video ID works, including Shorts, live and youtu.be links.
Why is the max-resolution image missing?
YouTube only generates it when the uploaded thumbnail was large enough. The HQ and SD versions are always available.