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Salmention is a protocol extension to Webmention to propagate comments and other interactions upstream by sending a webmention from a response to the original post when the response itself receives a response (comment, like, etc.). The original post then checks the response to the original, parses the response to the response (e.g. comment on a comment) and then displays it as an additional response on the original post.

Webmention with Salmention depends on understanding Webmention. Please read that first.

The name is a portmanteau of #Salmon and mention.

This is a Living Specification yet mature enough to encourage implementations and feedback.
Latest Published Version
discussion on #indieweb-dev (on Freenode IRC)
Ben Roberts
Tantek Çelik
Other contributors: revision history
Per CC0, to the extent possible under law, the editor(s) and contributors have waived all copyright and related or neighboring rights to this work. In addition, as of 2019-03-24, the editor(s) and contributors (2015-04-07 onward) have made this specification available under the Open Web Foundation Agreement Version 1.0.


Sending Salmentions

An implementation that sends and receives Webmentions can send Salmentions by doing the following:

When it receives and accepts a Webmention from a response to an original post:

  • Incorporate (or update) the response into the original post’s permalink by nesting the response inside the original, keeping track of whether any changes actually occurred.
  • If there were any changes (a new or updated response), then resend Webmentions to everything the original post sent webmentions to.

That act of resending those Webmentions when an original post is updated in response to responses is called “sending Salmentions”.

Receiving Salmentions

An implementation that receives Webmentions can receive Salmentions by doing the following:

When it receives a Webmention, in addition to normal Webmention processing:

  • Store the contents of the source of the Webmention in such a way that it can be rechecked in the future for any changes.

When it receives a previously received Webmention:

  • Check the source of the Webmention for any changes since the previous Webmention (using aforementioned stored contents), in particular any new responses to the source
    • E.g. check for new nested comment h-entry(s) inside the source’s h-entry
  • Incorporate any new response(s) to the source both into those stored contents, and display as inline responses to the target itself.
    • E.g. displaying a reply to a reply, as an additional comment on the original post.
    • If the previous Webmention generated a notification, then the new response(s) should as well.

The act of noticing a re-receiving of a Webmention and doing something when there are changes in the source, specifically nested responses, is called “receiving Salmentions”.

IndieWeb Examples

In order of implementation

Kyle Mahan

Kyle Mahan supports sending and receiving Salmentions on his site since 2015-06-09.

Ashton Macallan

Ashton McAllan supports sending and receiving Salmentions on her site since 2015-06-13.


Ben Werdmüller sneakily added suport for sending Salmentions on 2015-07-11[1].

Ben Roberts

Ben Roberts supports sending Salmentions on his site since at least 2015-07-12 and built his support to help pass SWAT0 as Player A.[2] Support for receiving was added since then (date unsure) [3]

Aaron Parecki

Aaron Parecki supports sending Salmentions since 2016-03-23, and receiving Salmentions on his site since 2015-07-12 and built this support to help pass SWAT0 as Player B.[4]


This section is closed. Please add to instead.

Awaiting original authors to move this issue to

Comment thread on separate page from post

This protocol requires that all replies be displayed on the same page as the post itself. I prefer to have the "conversation" on a second page, linked to from the post.

Idea: forward the webmention upstream instead of repeating the webmention from yourself. Then, upstream can parse the reply-to-reply, see that it is in reply to a comment in a conversation it manages, and add to the thread accordingly. No display of the replies on the intermediate site is required at all for this flow.



Main article: ActivityPub

ActivityPub describes a similar process to Salmention for propagating updates between systems. If one of your posts receives a mention (eg. as the target of a like, repost or inReplyTo, etc), your server should send the new post (the one that mentions you) to all recipients of your original post. (In ActivityPub, your server pushes your posts out to your followers, and retains a list of everyone posts are sent to, but this basically translates to sending a webmention to the original post).


Main article: Salmon

The Salmon protocol is a predecessor to #ActivityPub that broke useful conceptual ground but never gained widespread adoption. It's part of the OStatus protocol suite.

See Also