Alternatives to Spark for all platforms with any license

Pidgin

Pidgin is an easy to use, multi-protocol chat client client used by millions. Connect to AIM, MSN, Yahoo, XMPP, and more chat networks all at once. It has built-in...

Free Open Source Mac Windows Linux BSD PortableApps.com ... Xfce
Multiple protocols Multiple protocols support Extensible by Plugins/Extensions Supports XMPP ... Multiple languages Multiple Account support Multiple chat protocols Portable Video calling Voice Call Add a feature

1439 Like
Jitsi

Jitsi (previously SIP Communicator) is an audio/video and chat communicator with full end-to-end encryption that supports protocols such as SIP, XMPP/Jabber, ICQ/AIM...

Free Open Source Mac OS X Windows Linux Web Android ... BSD
End-to-end encryption Group chat iPhone/iPod sync Multiple protocols ... Multiple Account support OTR Video calling WebRTC Add a feature

275 Like
Trillian

Trillian is an instant messaging app that works on phones, tablets, and desktops while keeping your chats neatly synchronized between all of them! We think conversation...

Freemium Mac OS X Windows Linux Web Android ... iPhone Blackberry iPad
Facebook integration Multiple protocols POP3 Support Team Collaboration Add a feature

270 Like
Adium

Adium is a free and open source instant messaging application for Mac OS X, written using Mac OS Xs Cocoa API, released under the GNU GPL and developed by the Adium...

Free Open Source Mac
Customizable Multiple languages Multiple protocols OTR ... Supports XMPP Tabbed interface Support for Themes Add a feature

329 Like
Empathy

Empathy is a messaging program which supports text, voice, video chat, and file transfers over many different protocols. You can tell it about your accounts on all those...

Free Open Source Linux BSD
Built-in File transfer Multiple protocols Video calling Add a feature

154 Like
- Discontinued Empathy is currently unmaintained. Last version, 3.25, released in August 2017, can be still downloaded from the official website.
Miranda IM

Miranda IM is the smaller, faster, easier instant messenger with support for multiple protocols. Designed from the ground-up to be resource efficient while still...

Free Open Source Windows PortableApps.com
Multiple protocols Portable Add a feature

223 Like
Gajim

The goal of Gajim is to provide a full featured and easy to use Jabber client. Gajim works nicely with GNOME, but does not require it to run. It is released under the...

Free Open Source Mac OS X Windows Linux BSD Xfce
Encrypted chat Group chat Multiple languages OTR ... Supports XMPP Tabbed interface Video calling Add a feature

51 Like
Psi

Psi is an instant messaging application for Windows, Linux, and Mac OS X that connects to the free, open XMPP network. Localized versions of Psi are available in...

Free Open Source Mac Windows Linux BSD
Supports XMPP Add a feature

77 Like
IM+

Chat everywhere! IM+ is the most widely used mobile IM app! Connect all-in-one to MSN, Yahoo!, Google Talk, AIM, Jabber, ICQ, Facebook, MySpace and Twitter on ALL...

Freemium Web Windows Mobile Android iPhone Java Mobile ... S60 HP webOS Blackberry Android Tablet Windows Phone iPad Kindle Fire
Multiple Account support Multiple protocols support Add a feature

103 Like
YakYak

What does it do: * Send/receive chat messages * Create/change conversations (rename, add people) * Leave/delete conversation * Notifications * ...

Free Open Source Mac Windows Linux Hangouts
Portable Add a feature

17 Like
Disa

Disa is your new messaging hub. Conversations from different services can seamlessly be joined together, or disbanded within seconds.

Free Android Android Tablet Kindle Fire
Extensible by Plugins/Extensions Texting Unified messaging Add a feature

19 Like
Messenger for Desktop

A simple & beautiful app for Facebook Messenger. Chat without distractions on any Operating System.

Free Open Source Mac OS X Windows Linux
No features added Add a feature

9 Like
- Bundleware Be careful during the installation: https://alternativeto.net/discussions/applications/11718/be-careful-in-the-installation/
Tkabber

Tkabber is a Free and Open Source client for the Jabber instant messaging system. Its writen in Tcl/Tk, and works on many platforms (tested on Linux, FreeBSD, NetBSD...

Free Open Source Mac OS X Windows Linux BSD
No features added Add a feature

12 Like
KakaoTalk

KakaoTalk is a phone number based messenger service that allows users anywhere in the world to chat one-to-one or in a group for free. (no SMS service) Message...

Freemium Mac OS X Windows Android iPhone Blackberry ... Windows Phone Android Wear Kindle Fire
Group chat Based on phone number Secret chats Voice Call Add a feature

26 Like
Ayttm

Ayttm is an instant messaging (aka chat) client that provides all-in-one chat functionality for several major instant messaging services from one simple program. Ayttm...

Free Open Source Windows Linux BSD
No features added Add a feature

11 Like