This is so important for 'us', here on HN. Let me try to explain why: Many here are building SaaS products, and with the SaaS landscape getting ever more crowd

This is so important for 'us', here on HN. Let me try to explain why: Many here are building SaaS products, and with the SaaS landscape getting ever more crowded we see a lot of SaaS integrations emerge. Have a look at freshbooks for instance. Currently these integrations are usually implemented 'server-side': the server of one web app pulls data from another web app. If we want to allow client-side integrations, that allows a JS plugin to be loaded from another app, the we need to keep security in mind (as this is on purpose cross-site-scripting). This Caja lib seems to provide proper measures to allow these kind of integrations.