AppHarbor vs tsuru: What are the differences?

Developers describe AppHarbor as "Instantly deploy and scale .NET applications". AppHarbor is a fully hosted .NET Platform as a Service. AppHarbor can deploy and scale any standard .NET application to the cloud. On the other hand, tsuru is detailed as "Extensible and open source Platform as a Service software". tsuru is an open source polyglot cloud application platform (PaaS). With tsuru, you don’t need to think about servers at all. You can write apps in the programming language of your choice, back it with add-on resources such as SQL and NoSQL databases, memcached, redis, and many others. You manage your app using the tsuru command-line tool and you deploy code using the Git revision control system, all running on the tsuru infrastructure.

AppHarbor and tsuru can be categorized as "Platform as a Service" tools.

Some of the features offered by AppHarbor are:

• You push .NET and Windows code to AppHarbor using Git, Mercurial, Subversion or Team Foundation Server with the complimentary Git service or through integrations offered in collaboration with Bitbucket, CodePlex and GitHub.
• When AppHarbor receives your code it will be built by a build server. If the code compiles all unit tests contained in the compiled assemblies will be run. The result and progress of the build and unit test status can be monitored on the application dashboard. AppHarbor will call any service hooks that you add to notify you of the build result.
• If everything checks out the application is deployed and configured on AppHarbor application servers. AppHarbor can scale an application vertically and horizontally within seconds for better request throughout, performance and failover. AppHarbor balance load across all instances running that application. Scaling an application gives higher request thoughput, redundancy in case of instance failure and better performance.

On the other hand, tsuru provides the following key features:

• Fast and secure. The entire process is really simple with no special tools needed, just a simple git push.
• Scaling in Tsuru is completely painless. Just add a unit and Tsuru will take care of everything else.
• Tsuru is built to be extensible. Through services you can provide anything your application needs.

"Has a totally free account option" is the top reason why over 7 developers like AppHarbor, while over 4 developers mention "Very receptive to contributions" as the leading cause for choosing tsuru.

tsuru is an open source tool with 3.14K GitHub stars and 421 GitHub forks. Here's a link to tsuru's open source repository on GitHub.