Ranked in these QuestionsQuestion Ranking
Pro Code available to anyone to inspect or use, no spy- or adware
Mumble is available as a free download and source code is available on GitHub.
Pro Excellent voice quality
Since version 1.2.4, Mumble uses an audio codec named Opus that's specifically developed to provide low-latency voice communication over Internet. This means that there is no delay time, while audio still comes out clear.
A push-to-talk key allows you to only transmit audio when you want it. Others won't hear you chewing or your mom entering the room unless you want to.
Pro Low latency and resource usage
Dedicated servers and low overhead allows Mumble to have the least delay between users speaking and others hearing their speech, which can be very important for fast paced games.
Pro Easily overlay over game
An in-game overlay can be enabled to show users in the channel or users talking. Overlay can be disabled completely or on a per-game basis by going to Settings->Overlay. This allows for users to see their chat but not obstruct the game they are playing.
Pro Can be used on a gamers preferred platform
Available on Windows, Linux, OS X, Android and iOS which allows for the user to choose what operating system works for them and still be able to use Mumble.
Pro Free and open-source server software
The server software Murmur is licensed under a free and open-source BSD-style license.
Pro Free to download and use as a client
Mumble is completely free, even hosting your own server.
Pro Use of certificates offers more security and easy people management
Mumble uses certificates for user identification. A certificate can be generated by the user himself or issued by a third-party organization with organization certificates having 2 classes. A self-generated certificate is not tied to anything, a Class 1 certificate is tied to an e-mail address and a Class 2 certificate requires proof of identity. Depending on the server a different level of certification might be required.
Pro Server works on Raspberry Pi
Mumble server side is easy to setup and works smooth even on Raspberry Pi, which is pretty short on resources.
Pro Positional audio
Mumble supports positional audio for over 50 games, including versions of Call of Duty, Battlefield and Counter-Strike. This allows you to hear the audio from the direction of the player speaking, making gameplay more immersive and giving competitive players an edge. You can find a full list of supported games here.
Pro Secure & encrypted
This encryption is mandatory and cannot be disabled. The so-called control channel, which transports your chat messages and other non-time critical information, is encrypted with TLS using 256 bit AES-SHA. The voice channel carrying speech and positional audio is encrypted with OCB-AES 128 bit.
Pro Good audio normalization
Mumble includes great automatic volume adjustment functionality that can be used to prevent big volume changes while still allowing good communication.
By default, only users in the same channel can hear each other. Channels can be nested to better organize yourself according to what you want to be talking about.
Pro Portable version on PortableApps
Pro Server can be put on alternative firmware wireless routers
Con A bit more difficult to set up than similar solutions
The process of generating and/or acquiring certificates can be time-consuming and a bit more complex than setting up a username/password authentication that's found in other clients.
Similarly, setting up a server that includes configuring user permission system requires advanced technical knowledge.
Con Disconnect issues
Can have occasions of disconnect or users kept getting booted.
Con Relatively poor voice quality
While Mumble's voice quality is fine, and you can understand what's being said, there is a noticeable difference between it and many other platforms.