* Frontend - Run thousands of Jasmin unit tests with PhantomJS. Run Cucumber specs against your Rails app with Chrome Driver with 20 different strongly-isolated server / client pairs in parallel. Ruby, Python, Java, Node, Go, and more. CircleCI is flexible to work in your environment. * Backend - Whether you have a Rails monolith or a network of Node.js microservices, CircleCI can handle any backed platform that runs Linux. We also support dependencies from Postgres to Docker or anything else you care to sudo apt-get install. Oh and did we mention we run everything really fast? * Mobile - Android or iOS, hybrid or native, you can build and test your mobile app on CircleCI. Got some backend services for your mobile app? Let us build, test and deploy those for you. * Docker - CircleCI has been built on Linux containers from the start so when Docker took off, we were excited for a chance to put our container skills to work for our customers. Anyway, we think we’ve built the best solution to taking your app from Docker files to production. * Source - CircleCI builds start right away with a hook from GitHub. No plugins to worry about, and no polling. Granular checkout key options support pulling from multiple projects and our source caches ensures that checkouts are lightning-fast. * Resolve Dependencies - CircleCI automatically uses language-specific tools like rvm and virtualenv to ensure dependencies are installed into an isolated environment. After the first build, the CircleCI dependency cache saves all your dependencies so they can be re-installed in no time from the next build moving forward. * Build - Not every language requires a compilation step, but if yours does, we're standing by with all of your favorite build tools. We have compilers for Java (many versions), Scala, Haskell, CoffeeScript, Less, and more ready to go. We also support your favorite build tools, like Gradle, Maven, Leiningen, and Cabal. Perhaps you're writing Smalltalk or OCaml, well those might not be preinstalled, but you can always sudo apt-get to suit your build environment. * Test - It goes without saying that CircleCI should be really smart about running your tests. We think we do it better than anyone else with our automatic test parallelization and detailed test failure reporting. CircleCI has first-class support for a pile of test runners, from RSpec to Nose, but we can handle anything that returns an exit code.

* Technology Awareness - One reason TeamCity is dubbed an "Intelligent CI server" is its approach to integration. When we say we support a tool, we mean it in every way possible. For example, support for Visual Studio projects provides automatic detection of tool versions, testing frameworks support, code coverage, static code analysis, and more. And the best thing is, you get all this support without installing any plugins and with no modifications to build scripts! * Configuration - Skillful software developers try to avoid code duplication; similarly, build engineers avoid duplication of settings. TeamCity understands this and provides several ways to reuse settings. * VCS Interoperability - TeamCity version controls systems integration is comprehensive. It’s hard to imagine a project whose source code couldn’t be retrieved by TeamCity. * Key Integrations - It’s impossible to imagine a great CI and CD server without an integration with some key tools like your version control, you issue tracker, your build tool, and your package repository. TeamCity takes it very seriously to provide full support for these key integrations. * Build History - We believe that keeping a history of builds, changes and failures is crucial to the success of any software development process. TeamCity enables you to run history builds, see statistics and test history reports, as well as pin, tag, and add builds to favorites. All of the changes are accumulated in the change log. * Extensibility and Customization - TeamCity provides you with multiple ways of interaction, customization, and extending your server. Use service messages in your build scripts, interact via REST API, or create plugins for TeamCity using Open API. * Cloud Integrations - TeamCity takes advantage of cloud computing by dynamically scaling out its build agents farm on Amazon EC2, Microsoft Azure, and VMware vSphere. * Build Infrastructure - Imagine a conveyor belt of changes from developers and a bunch of testers taking the changes, verifying them and complementing these changes with verification results. TeamCity is such a conveyor, except that testers are replaced with Build Agents. * System Maintenance - TeamCity helps you maintain your CI server healthy and stable even when no builds are running so that you don’t waste your time when it’s needed the most. It provides you with useful reports like Disk Usage, Build Time, and Server Health reports