"...For about the past two years, WhatsApp has been building a way for other messaging apps to plug themselves into its service and let people chat across apps—all without breaking the end-to-end encryption it uses to protect the privacy and security of people’s messages. ... In September, European, lawmakers designated WhatsApp parent Meta as one of six influential “gatekeeer” companies under its sweeping Digital Markets Act, giving it six months to open its walled garden to others. With just a few weeks to go before that time is up, WhatsApp is detailing how its interoperability with other apps may work. ... Matthew Hodgson, the cofounder of Matrix, which is building an open source standard for encryption and operates the messaging app Element, confirms that his company has worked with WhatsApp on interoperability in an “experimental” way but that he cannot say any more due to signing a nondisclosure agreement. ..."