Huh. imgbox is still as it has been on my end and hasn't raised any flags in any of my browsers, but in any case I tested out ImgBB (bear in mind it was simply the first Google result) and it appears to work similarly.
If you happen to have images with particularly small filesizes—we're talking 32 kB or fewer—and don't mind potentially really long strings of text in src attributes, you can also forego hosting entirely and convert them into data URIs.