Free node/mongo dev server instead of open shift?

We've been using openshift's free small server to rapidly prototype apps and ideas, migrating ones that make the grade to commercial servers.

Openshift's free small gears have been invaluable in being able to test a lot of different ideas, but they're retiring that service and I'm not clear if the new NextGen service will allow these small projects for free.

Does anyone know of other services where we can spin up free small servers to test ideas on before migrating successful ones to paid servers?