YouTube Thumbnail Viewer. I wanted to find the best quality thumbnail image for a YouTube video, so I could use it as a social media card. I know from past experience that GPT-4 has memorized the various URL patterns for img.youtube.com, so I asked it to guess the URL for my specific video.
This piqued my interest as to what the other patterns were, so I got it to spit those out too. Then, to save myself from needing to look those up again in the future, I asked it to build me a little HTML and JavaScript tool for turning a YouTube video URL into a set of visible thumbnails.
I iterated on the code a bit more after pasting it into Claude and ended up with this, now hosted in my tools collection.
Recent articles
- Useful patterns for building HTML tools - 10th December 2025
- Under the hood of Canada Spends with Brendan Samek - 9th December 2025
- Highlights from my appearance on the Data Renegades podcast with CL Kao and Dori Wilson - 26th November 2025