True historical builds
Reproduce any of your builds at any point in time, dated back to as long ago as your VCS allows.

Different settings in different branches
Store different build steps and parameters in different branches, and apply them when needed, in any way you need.Personal builds with personal settings.

Change project settings in your IDE, and see how they can work out for your project by running a personal build with these custom settings. If you use the pre-tested commit option, the settings will be committed and applied to your server configuration right after a successful build.

Added support for Perforce and Subversion
From now on you can also use Perforce and Subversion version control systems for storing your settings.

The full list of supported VCSs for Versioned Settings now includes Git, Mercurial, Perforce, and Subversion.

Support for NUnit 3.0
TeamCity 9.1 comes with enhanced NUnit support: not only is the latest NUnit 3.0 supported in TeamCity NUnit runner, but NUnit also detects if it is run by TeamCity. This provides guaranteed compatibility with all upcoming features of NUnit and TeamCity.

Visual Studio support
Visual Studio 2015, TFS 2015, MSBuild 2015, MSTest 2015, FxCop 2015, and Powershell 5 are supported.

Visual Studio Tests Runner
MSTest and VSTest are combined into a single Visual Studio Test Runner and supported out of the box, so that you don’t have to worry about installing additional plugins.

Pumped up security 9.1
TeamCity 9.1 comes with unidirectional Agent-Server communication which adds an extra level of security for your build agents. It simplifies your firewall configuration by eliminating the insecure, HTTP connection from the server to agent, making it possible to use HTTPS protocol only.

Additionally, 20+ security issues have been fixed.

Project reordering
Change the order of your projects and build configurations on the Projects Overview page to better reflect your actual projects’ structure.

Chart reordering
Set the order of charts in a way that’s most informative and convenient for you and your team.

Coloring and URLs in build logs
Important details will never escape your notice thanks to ANSI coloring, as well as URL highlighting in build logs.

Truncated build configuration path
Visual noise reduced thanks to truncation of paths to build configurations. The truncated paths are resolved based on the current context.

Easily move projects between servers
Plan less, do more. Rearrange projects between servers freely with the project import feature. Preserve full project and changes history, as well as user profiles, while doing this right from the TeamCity interface.

Store project settings in Version Control
Never lose track of your settings! Store your project settings in a Version Control System (Git or Mercurial, more to be added later) just like you do with your source code, and use your favorite tool to review and audit them. Review changes, see diffs, roll back in case you change your mind, and if one of your colleagues messes with those settings again, you’ll know who it was! Fun, right? See how easy it is to be in total control of your building process.

Zero server maintenance downtime
Wait no more for TeamCity to run a clean-up! Running a large setup, or working in a remote team covering all time zones around the globe? No longer let downtime be an issue: from now on TeamCity runs the server clean-up in the background, so that you can enjoy zero downtime and allocate all the server time for your builds. We promise you’ll forget what clean-up was in a week.

Edit charts in UI
Create and modify custom charts right from TeamCity UI. Make your project or build configuration statistics look beautiful, without any XML editing.

Using Microsoft Azure cloud platform? Integrate it with TeamCity and scale out your build farm when needed. Don’t bother predicting the load on your build agents during releases anymore. TeamCity will automatically start agents on Azure when you need more power, and stop them when they are no longer needed.

Using Visual Studio Online? Set up VSO as your source control in TeamCity (both Git and TFVC are supported), link TeamCity builds and version control history with VSO Work Items, and receive TeamCity notifications directly in your Team Rooms.

TeamCity always aims to give your team more build power, and for those of you taking advantage of local cloud capabilities with VMware vSphere, this integration will surely be an asset. Now you can use remote TeamCity agents installed on VMware virtual machines to process builds more efficiently: TeamCity analyzes the build queue and launches virtual machines with the TeamCity agents matching queued builds.