Disclosure: I work on MongooseIM.
I recommend one of the Erlang-based servers: either MongooseIM or ejabberd. MongooseIM was originally a fork of ejabberd, but the codebases have diverged quite a bit in recent years.
These servers stand out among the other options not in terms of feature-richness (they do offer lots of features, though), but because they ...
Xabber (free/libre except for the logo, according to a friend) can do it.
I'm also told mcabber can do it, although the references are sparse; it looks like there is/used to be a plugin needed, and in the current version, the UI marks contacts that want attention from you with an exclamation mark (as opposed to the regular hash sign).
Pidgin is FOSS, uses the open-source Libpurple, and officially supports XEP-0224 through Libpurple.
You can use the /attention command. You can also check their Supported XEPs page for more information.
You can have a look at Libervia, which is the web interface of Salut à Toi.
I think it's pretty much what you are looking for. It's AGPL v3+, very actively developed, and has "social" features like (micro)blogging. I'm working on it, and you can ask us if you need a feature.
There are also Jappix and Movim which are other XMPP/Web projects.
https://conversejs.org/ can be used for this.
It supports logging into any public jabber using a httpbind protocol either on their page or you can integrate the chat into your web page.
It even supports OTR.
Gajim seems to support it in its beta version (0.16). (That is why it’s not included in their list of supported XEPs yet.)
The feature was requested in 2007 and added in 2012.
You can use it via the /attention command.
Note there there is currently some kind of attack possible: /attention vulnerability with notification
Single user jabber servers feel like overkill - you're going to need to federate with other servers to get any use of it (and this needs to be turned on at the other server), and no current package is designed for a single user as a result. I have set up and run openfire and its well documented, easy to maintain and really easy to administer. You can get one ...
Since your requirement is iOS, I'd recommend IM+ (App Store Link). It supports a variety of networks, including Yahoo IM and Google Talk, as well as push notifications. There is a Pro version, as well.
If you're looking for a desktop client when you're at home, IM+ supports a web interface, but I'd actually recommend Pidgin for that purpose.
The app I've used in the past is Trillian It's a good program, does what you require, and works on all platforms. Go pro, and no adds for life, it's a small fee for a long term commitment.
Trillian also is always upgrading and updating their software, and has been around for a very, very long time. I like their support system, and they don't look like they ...
Gajim (Wikipedia article) is a free/libre XMPP client. It exists since 2004 and is still maintained.
It’s available for BSD, GNU/Linux, and Windows. I’m using it as my primary XMPP client on GNU/Linux. I tested it on a Windows system once and everything seemed to work fine there, too.
XEP-0280: Message Carbons
XEP-0313: Message Archive ...
Pidgin was your best shot for cross-platform, and while the OTR support comes from a plugin, it's still there. I can't make any recommendations to make the UI better, though, and it is pretty craptacular.
But there are other applications with OTR support, or plugins that allow you to add OTR support to other clients. See https://otr.im/clients.html for a ...
There are two different clients you can use.
First one is Adium, which is around for quite some time and supports XMPP and much more (like AIM, Yahoo, GChat...) and has OTR support.
Second one is Tor Messenger. It's a fork of Instantbird (Mozilla's chat client) and has support for XMPP and OTR. Also it gives you an extra layer of security with using Tor ...
I suggest you give Conversations a go which unfortunately is Android-only, but has most features one would expect from a modern Jabber/XMPP client:
Send images and other files, easily from other apps via the "share" button
Support for conferences (group chats)
Support for various encryption protocols (OMEMO, OTR and OpenPGP)
Some XMPP/Jabber clients (I am ...
You can try Jitsi.
Its a XMPP and VoIP client and it's lightweight as you want.
I was using it in Windows for almost a year and I never got more than 20MB of ram in task manager.
As a plus, I used other XMPP clients but neither of them has a easy configuration like Jitsi.
https://github.com/xmikos/qhangups is a PyQt application, that is a GUI interface to the command-line client at https://github.com/tdryer/hangups, that was created by reverse-engineering the undocumented Hangouts API.
It doesn't seem to work for me but seems promising. I would like to see it gain momentum, contributors etc.
Jitsi advertises "secured video calls, conferencing, chat, desktop sharing, file transfer, support for your favorite OS and IM network."
It supports protocols including SIP,
Facebook (via XMPP),
.NET Messenger Service (commonly known as MSN or Windows Live Messenger),
And has these Security ...
Loqui IM (included in Firefox Marketplace) is a chat client supporting XMPP.
It’s FLOSS, licensed under GNU AGPLv3.
You’ll notice that it’s an alpha version. Currently, there are some bugs with the XMPP implementation, but it seems to be actively developed. I can’t recommend it as a stable solution at the moment, but I’m sure it will improve over the next ...
Gajim (FLOSS; available for GNU/Linux, FreeBSD, Microsoft Windows) supports OpenPGP by default.
Your own key:
Open the accounts menu (Ctrl+Shift+a).
Select an account.
Go to the tab about personal information.
Under the "OpenPGP" section, press the button for selecting a key.
Select your key from the list.
Now when you go online with this account, you ...