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Continuing the discussion from Threema, a good alternative to Skype?.
Signal
(Former TextSecure and Redphone)
Platforms: Android, iOS, CM, crossplatform Desktop app (based on electron)
Can (video) call and send texts, photos, GIFs, videos, audio, contacts, location, arbitrary files, etc. [up to 100MB]
end to end encryption (audited and trusted by the crypto community and endorsed ie by Edward Snowden)
easy to use (Similar Functionality as WhatsApp, therefore easy for people that are used to WhatsApp.)
free
independent (developers are supported by [community] donations and grants)
run by a non-profit organization: https://signalfoundation.org/ Link to: wikipedia article.
open source
Video calls
Automatically scans telephones contacts for other Signal users. But with privacy in mind: https://signal.org/blog/private-contact-discovery/
can additionally also be used as standard SMS, MMS messenger (unsecured)
Easy to switch which SIM card to use when sending SMS (only on Android 5 and higher. Long press and select on send button.)
Signal reduced metadata storage to a minimum, only the date of registration and the last day you connected to the service gets stored. More info here)
There is also a version, which works without Google Cloud Messaging (GCM) (https://signal.org/android/apk/ This version uses websockets and may consume more battery than the GCM version. It will auto-update itself)
multi-device support
possibility for disappearing messages
Ability to send any kind of files (.pdf, .doc, etc.)
can additionally be installed through Yalp, without Google Account and without Google Mobile Services. Yalp is available in F-Droid.
lack of widespread user base
not available on F-droid (but in https://fdroid.eutopia.cz/ LibreSignal [abandoned]) / currently need of Google account for Android-Version, see discussion on Github) (install APK from signal.org or via Yalp, see above)
Walled-garden: your buddies have to use Signal as well!
registration via telephone number only
Skype
Video calls
communicates with computer-based users
no telephone number needed for registration
Closed source
Owned by Microsoft: Intelligences like the NSA are able to intercept your calls
Walled-garden: your buddies have to use Skype as well!
no end to end encryption
Telegram
Platforms: Android, iOS, Windows Phone, FirefoxOS, UbuntuTouch, Browser, Mac, PC, Linux
Can share photos, videos, audio, contacts, location, files, etc.
Telegram client is open source
Similar Functionality as WhatsApp, therefore easy for people that are used to WhatsApp.
Ability to send any kind of files (.pdf, .doc, etc.)
Automatically scans telephones contacts for other Telegram-users
Telegram server not open
Questionable encryption (see Wikipedia)
end to end encryption is deactivated per default
group chats can’t be end to end encrypted
lack of widespread user base
Walled-garden: your buddies have to use Telegram as well!
registration via telephone number only (you can choose a username so that other users cannot see your phone number)
Threema
Platforms: Android, iOS, Windows Phone, Blackberry, Amazon Fire OS
A full-grown messenger with focus on privacy and encryption.
End to end encryption
Lots of privacy settings
Ability to send any kind of files (.pdf, .doc, etc.)
New design, clean look
Ability to do surveys
Works without Google Cloud Messaging (GCM) and polls new messages every 5/15/30 minutes
Can be used completely anonymously
Lacks users, not very widespread
Account bound to one device
Closed source, thus claimed encryption cannot be verified
No test version
Walled-garden: your buddies have to use Threema as well!
One-time purchase of license (no recurring charges)
Platforms: Android, iOS, Blackberry, Symbian, Nokia S40, Windows Phone, Browser
Can share photos, music, contacts, videos, voice messages.
It is the most widespread messenger.
end to end encryption (provided by OWS, the makers of Signal)
Belongs to Facebook, hence connected to privacy concerns – they do analyze your metadata
Walled-garden: your buddies have to use Whatsapp as well!
Closed source, thus claimed encryption cannot be verified
they copy all phone numbers in your address book on their servers
registration via telephone number only
XMPP Clients (Conversations/Xabber)
XMPP is a robust, well established protocol upon which applications can build for easy and interoperable messaging.
extensible through XEPs (XMPP Extensions).
Does not require a Google Account or specifically Google Cloud Messaging (GCM)
No walled-garden: Your buddies can use ANY XMPP-Server to chat with you! (XMPP is a federated protocol, which means you can freely choose a trustworthy server for yourself while still chatting with contacts that are using other servers. Just like you can send emails from @fairphone.com to @gmail.com etc.)
can be used completely anonymously
No secure encryption as default
lack of widespread user base, but it is possible to change!
Conversations
Platforms: Android 4.0+ (But you can use ANY other XMPP software at various platforms to chat with)
Conversations is a Jabber/XMPP client for Android 4.0+ smartphones that has been optimized to provide a unique mobile experience.
Design principles
• Be as beautiful and easy to use as possible without sacrificing security or privacy
• Require as little permissions as possible
Fully Open Source, free at F-Droid, or at Playstore, a free and easier-to-get-started version is Quicksy!
end-to-end-encryption (OMEMO) available with open source (also PGP and OTR support)
You can use ANY XMPP/Jabber² service you like (existing thousands), Creating new account can be done via the App, only username/password neccassary!
high grade of privacy: none private informations are gatherd (no Adressbook crawling)
Not available for non-android-based telephones (though XMPP clients exist for every platform and are interoperable)
Kontalk
Platforms: Android (Play Store, F-Droid), Java client (requires Android app at the moment)
Automatically finds all contacts in your address book using phone number hashes as Jabber ID
Version on F-Droid doesn’t connect to GCM (Connection policy)
FLOSS
end-to-end-encrypted
very customisable
No group chat (will be implemented in December 2016)
No flawless federation with other XMPP networks yet.
Xabber
Platforms: Android 4.0+ but an alternative version (FDroid link) is available and still updated for devices between Android 1.5 and 3.2.
Advantages and inconvenients are quite the same as Conversation’s, though it’s UI is different and :
Highly customisable
Support for old versions of Android
Less encryption options
Facebook Messenger
Belongs to Facebook, hence connected to privacy concerns.
end to end encryption is deactivated per default
SIMSme
end-to-end authentication and encryption
self-destroying messages possible
Walled-garden: your buddies have to use SIMSme as well!
Wire
Platforms: Android, iOS, Linux, macOS, Windows, Internet Browser
everything is end-to-end encrypted (audiocalls, videocalls, text, pictures, files)
ability to send any kind of files up to 25 mb (.pdf, .doc, etc.)
communicates with computer-based users
clients and server are open source (see Golem.de)
self-destroying messages possible
free
use of telephone contacs is optional (and anonymized, only hash values of contact data is submitted)
multi-device support
Works without Google Cloud Messaging (GCM), uses WebSocket connection instead
Possibility of registration with mail address only
lack of widespread user base
not available on F-droid yet (but APK file is directly available from website)
Walled-garden: your buddies have to use Wire as well!
Ring
Platforms: Android, Linux, macOS, Windows
everything is end-to-end encrypted (audiocalls, videocalls, text, pictures, files)
no central server, completely p2p
free
multi-device support
registration via telephone number only
Tox
Platforms: a variety of clients is available for Android (with own F-Droid repo), Linux, macOS, Windows, iOS
everything is end-to-end encrypted (audiocalls, videocalls, text, pictures, files)
no central server, completely p2p
free and open-source
multi-device support
can be used completely anonymously
Walled-garden: your buddies have to use Tox as well!
no offline messaging, both contacts have to be online at the same time to chat (and even to complete a friend request)
RCS(-e)/Joyn/Message+
Standardized.
No walled-garden: The app is provided by your mobile provider.
No additional account required.
It’s planned that this is pre-installed on future devices.
Must be explicitly supported by your mobile provider.
Now, it’s not pre-installed. Your buddies have to install the app too.
Prices are not consistent. Someone could use it for free, other must pay per call minute or message. Criticized as an attempt of the mobile providers to make more money.
coupled with telephone number
Old-school: SMS
Standardized.
Supported by nearly every mobile phone, even the old dumbphones. Or you can use a specialized website or some webmails for writing SMS messages.
You have many choices which app you use for SMS.
SMS can also be sent or arrive without Wi-Fi/mobile data connection.
Possibility of automatically sending messages
Plain-text only. You cannot send formatted text, images, photos or videos with SMS messages.
Not necessarily included with your data plan. If you have to pay per-message, you pay the per-message fee per 153 characters if your message exceeds 160 characters.
No end-to-end encryption out-of-the-box (check Silence app solution).
coupled with telephone number
Old-school: MMS
Standardized.
Supported by nearly every smartphone, old mobile phones will receive a SMS message with instructions to get the message with a computer anyway. Or you can use a specialized website or some webmails for writing MMS messages.
You have many choices which app you use for MMS.
Possibility of automatically sending messages
Support for formatted text, images, pictures, videos, …
Very high per-message fees (for example 0.39€)
No end-to-end encryption out-of-the-box (check Silence app solution).
Some mobile providers disabled MMS because of the Stagefright security hole.
coupled with telephone number
Old-school: E-mail
Standardized.
Nearly every person has an e-mail account.
E-mails can be sent and received by nearly all communication devices (on PC/laptops with application or webmail, smartphones/tablets, even some dumbphones and printers).
You have many choices which app you use for e-mail.
Possibility of automatically sending messages
End-to-end encyryption possible with S/MIME, OpenPGP or encrypted files.
You can attach files of every type on a message.
Not all e-mail applications support all features (such as HTML e-mails or end-to-end encryption).
Chatting is not really comfortable.
However I suggest to not add it as its own point, but include it in XMPP-clients (e.g. “Conversations / Xabber”).
The license can alternatively be purchased on the official website. You won’t receive automatic updates if you choose that way but it is possible to update manually from inside the app.[/quote]It’s not true, I bought the app from their Website together with licences and get iformation about updates on automatic.
Currently