On Apr 2, 2015 10:05 PM, "Daniel Friesen" <daniel(a)nadir-seen-fire.com>
wrote:
Twitter exclusively uses their proprietary Twitter
cards markup ( <meta
name="twitter:card" content="summary" /> ...) and requires you to
validate and submit your site for approval before they'll display cards.
This isn't quite correct. They have their own thing, which allows you to
give some Twitter-specific data, but attributes that are pretty standard
(like thumbnail image) will fall back to open graph.
https://dev.twitter.com/cards/markup
You do have to submit a request, though, for cards to be shown. I think
it's a pretty painless process, but I wasn't the one handling it when we
implemented card support.
Reddit uses embed.ly, which is supposed to support a
variety of Open
Graph, oEmbed, etc...
Depending on what embedly tells us it can embed given certain conditions
(for instance, the embed needs to support https if the requested page was
https), we sometimes use embedly for thumbnails, and sometimes use our own
scraper, with the code I linked to in my first email. It will currently
pick up on opengraph tags, but if you decide to implement another standard
we don't currently support, I will gladly build it in (pending some project
scheduling, so perhaps not immediately).
From what I've seen, the various web-chat
irc-replacements support open
graph as well, if they do any auto-link-embedding.