Many, many of them. See the gist posted in another comment: https://news.ycombinator.com/item?id=29543439 https://news.ycombinator.com/item?id=29543439 Though

Many, many of them. See the gist posted in another comment: https://news.ycombinator.com/item?id=29543439 https://news.ycombinator.com/item?id=29543439 Though even that long list is missing many. I have lots of emails in my inbox from various software vendors that are NOT listed in that Gist. It's probably easier to compile a list of software you use that uses java, then the short of those projects that DON'T use log4j.