Best practices in evaluating new software

With limited exception, user-facing software chosen by the Wikimedia Foundation should follow the principle that the code would be able to pass Wikimedia's standard code review process. This means that the software chosen or developed to add a new site/service or enhance an existing one will:

be free and open source;
conform to Wikimedia's values (global audience, no privacy-invading analytics software, etc.);
have a localizable, internationalized user interface;
more in general, scale beyond the initial goals without bias (e.g. not USA-specific, not locked into a single wiki/project);
not reinvent the wheel/duplicate existing friend efforts for similar goals (e.g. extensions must use MediaWiki's standard frameworks as much as possible, we won't create a competitor of LibreOffice, we probably won't try to duplicate phpBB or LiquidFeedback within MediaWiki);
ideally, as byproduct of our needs and of any non insignificant effort, also set a standard and offer reusable components and libraries to other free culture projects.

See also