>>10238375I understand sufficiently little about the ecosystem that I don't see any immediate issues.
It's probably more efficient to offer a second endpoint that merely proxies images in case you can't just hotlink them rather than embedding them in Base64. Also serving them with the correct MIME type – only the sample images are always JPEGs, whereas the full image can be PNG too. There's no value for that in the JSON, you would have to derive it from the file extension.
I'm still thinking about a better way to pick any truly random image, not just using a random offset up to 25000. But there's probably none if the booru does not offer a random ordering e.g. like derpi does.
(Also, are all-caps IDs somewhat rare? By my calculation that is 1 in 1348 chance, whereas kot ID is 1 in 5461.)