Is there such a word as "lightweightness"?

Is there a good translation for the German word "Leichtgewichtigkeit" (lit. "lightweightness")?

According to leo.org and dict.cc, there is none, but according to these translations, there are several.

What I want to express is that there is "...lightweightness compared to...". I don't want to use the adjective "lightweight" but a noun.

Is there a better choice?

EDIT: I want to describe that an API is not as extensive/expensive as others. Thus, lightness is not what I'm looking for.

Solution 1:

Lightweight can function both as a noun and an adjective. To describe your API, you could say:

• This API is a lightweight interface with minimal features.

In technical circles, no-frills is another term used to describe minimalistic protocols.

• This is a no-frills API with minimal features.

Solution 2:

Given that your context is to describe an API is not as extensive/expensive as others, I suggest simplicity.