Re: Standardizing the printed and HTML version of a an ActivityPub handle

So, this is a really interesting topic!

In terms of the "right" format for ActivityPub accounts, I'd suggest 
sticking with bare Webfinger, username@domain.tld. If I were make a UI 
for submitting Fediverse account IDs, that's probably the format I'd use.

 From the URI perspective, for Webfinger identifiers, 
`acct:username@domain.tld` is the "right" way to do it.

Having that be clickable means that users can assign apps to "handle" 
the URI. For example, a user could assign the Elk.zone Web application 
to handle those URIs, and show the profiles page with profile, outbox, 
followers, friends, etc. as well as affordances to follow, block, 
message, mention, etc.

There are browser features and operating system features to define a 
handler for an URI protocol prefix. For browsers, 
registerProtocolHandler() is the way to go.

https://developer.mozilla.org/en-US/docs/Web/API/Navigator/registerProtocolHandler

Theoretically, assigning an app to handle the "acct:" prefix would let 
you create a link like this in HTML:

<a href="acct:evan@cosocial.ca">Evan Prodromou</a>

...and it would just work.

There are two problems with this, though.

1. Webfinger identifiers are primarily (?) used for ActivityPub actors, 
but not exclusively. It seems like a low risk, but some non-zero 
percentage of users might want Webfinger addresses to be handled by... 
something else?

2. HTML5 has an allowlist of URI prefixes that can be registered to be 
handled, and "acct:" is not on the list. You *can* use whatever prefix 
you want, as long as it start with "web+", so registering the 
"web+acct:" prefix would let you write links like this:

<a href="web+acct:evan@cosocial.ca">Evan Prodromou</a>

Anywho, long story short: I did a little experimentation with this on 
https://acct.swf.pub/ ; you can register that web site to handle 
web+acct: URIs, and it should then handle them correctly. 
(https://acct.swf.pub/test.html has a test link you can try). I need to 
get back to polishing it up, but I think this is an interesting area to 
pursue.


On 2025-09-16 4:31 p.m., Johannes Ernst wrote:
> During registration for FediForum (which is coming up again, by the 
> way!) we are asking people for their social web handles:
>
> Here is a selection of what they give us when they probably mean 
> ActivityPub
>
> @foo@bar
> AP: @foo@bar
> https://bar/@foo
> foo@bar
> foo (???)
> acct:foo@bar
>
> Is it time to define a canonical version?
>
> Perhaps there could also be a canonical, clickable HTML version.
>
> Just a thought.
>
> Cheers,
>
>
>
>
> Johannes.
>
>

Received on Wednesday, 17 September 2025 21:16:45 UTC