It's uncommon for user facing stuff, but only a little uncommon on the API side for abuse rate limiting. I know curl supports it. This kind of code is useful a

It's uncommon for user facing stuff, but only a little uncommon on the API side for abuse rate limiting. I know curl supports it. This kind of code is useful anywhere you have message buses with finite resources, which is a lot broader than just HTTP. It lets you separate the how of data processing and transformation from the when. I keep a token bucket header in my personal toolbox for embedded work because it's just such a common and simple building block.