Hey chuyeow, nice to see you like Passenger.

The Open Source version of Passenger will always be our core product, and it will be maintained and developed just as it always has been.

Phusion Passenger Enterprise is a set of features added on top of the Open Source version, to add stability and deployment features to high performance applications. As Ninh posted earlier, we are working on a direct comparison table to make the differences more clear.

Because Passenger Enterprise is built directly on top of Passenger Open Source, both versions are always released in tandem. This means that Open Source 4.0 and Enterprise 4.0 will be released at the same time.

+1 for ETA. Also - there is one thing more, that is unclear - I know, that you will not limit functionality of OS Passenger and it's still fully legit to use current version, but it would be great, if you could exclusively mark it somewhere, that this wouldn't be unclear. Or just create some kind of FAQ. You know - after all MANY people are using your software and once you've decided to start offering paid version, there are doubts about future etc

Hi Chuyeow, glad you like it. The open source version of Phusion Passenger 4 is already available, and has been for a while now. It hasn't reached beta status yet, but you can find the code in the 'experimental' branch on Github. Phusion Passenger 4 contains many rewritten subsystems, allowing it to perform better. It also supports multiple Ruby versions.

There's no need to hold on to buying Enterprise. All Phusion Passenger 4.0 open source features will become immediately available to Enterprise users. We also have some more Enterprise-only features planned for the future, and we will be announcing them on our blog.