2021-06-04 UTC
# ↩️ WebSub/PuSH is supported by a number of feed readers; I did a brief survey of support about two years ago (which could probably stand to be updated): https://beesbuzz.biz/blog/2655-WebSub-support-update
mf2 and webmention are very heavily used by #indieweb folks. ( twitter.com/_/status/1400866216726650881)