only as long as everyone follows the same rules. Each driver must
both know and follow the rules. To be effective coordination devices,
interface standards must be binding on both the platform owner and
app developers; app developers must obey them and also expect
others to obey them (Baldwin and Clark, 2006; Ostrovsky and
Schwarz, 2005). The degree to which an app actually complies
with interface specifications encapsulates its behavior in practice. This
in turn can generate variability in compliance among different app
developers, with some app developers closely complying with the
standards prescribed by the platform owner and others doing it half-
heartedly. This variance in interface standards compliance among
apps coupled with differences in app microarchitectures often creates
variability in the architectural properties of different comparable apps
even within the same platform. However, such compliance cannot
readily be enforced, is rarely contractible, and is costly to verify
(Ostrovsky and Schwarz, 2005).
Compliance with a platform’s interface standards requires a carrot—
demonstrable value and benefit to app developers—rather than a
stick. What’s in it for an app developer? Interface standards
compliance decreases the complexity that an app developer must
cope with, and the depth of knowledge about the platform that she
needs to possess in doing her own work. This rationale, however,
works better for established interfaces that have already been adopted
by other app developers in a platform than it does for new interface
standards. Early adoption of a new standard or API by an app
developer can be particularly risky, especially one that develops the
app on multiple rival platforms (i.e., produces a multihoming app). The
platform owner must therefore credibly assure app developers against
the risk of being stranded with high dependence on a platform
interface standard that could be abandoned at will and also
communicate precisely how it can enhance the app developer’s own
work. The platform owner must make it easier and less costly for app
developers to adhere to the platform’s interface standards and
specifications. This requires investments by the platform owner in
creating good app testing mechanisms that app developers can use
themselves, and also in tools to help the platform owner determine
