“There’s real tension between offering an easy way to offer this interoperability to third parties whilst at the same time preserving the WhatsApp privacy, security, and integrity bar,” says Dick Brouwer, engineering director at WhatsApp. That tension is now being tested in the wild, as WhatsApp begins rolling out a beta feature that lets users exchange encrypted messages with people on other apps starting with BirdyChat in select European regions.
The change is propelled by the European Union’s Digital Markets Act, known as DMA, which obliges selected “gatekeeper” platforms to expose their services to their competitors. For messaging apps, this means allowing cross-platform communication without undermining end-to-end encryption. WhatsApp, with more than two billion users around the world, is the first major service to meet such interoperability under the DMA’s rules.
In technical terms, it extends WhatsApp’s current client-server architecture by having third-party applications connect directly to WhatsApp infrastructure. In order to ensure message confidentiality, Meta recommends that the partner applications implement the Signal Protocol, which is the same cryptographic framework WhatsApp uses. In practice, this means that the content should be encrypted with the Signal Double Ratchet algorithm, wrapped in XML “message stanzas,” and then transmitted over HTTPS. WhatsApp allows apps utilizing other encryption methods, provided they can demonstrate that their solution offers equivalent security standards, but doing so requires going through WhatsApp’s compliance checks.
Interoperability, for the time being, is restricted to one-on-one chats. Users can exchange text, images, videos, voice notes, and documents, but, more advanced WhatsApp features like stickers, status updates, and disappearing messages are yet to come. Messages originating from other apps show up in a dedicated “third-party chats” section at the top of the inbox, though users can combine them with regular conversations if that is preferred. The feature is opt-in, meaning cross-platform messages won’t arrive unless the user explicitly enables the setting in Account > Third Party Chats.
Maintaining end-to-end encryption across different platforms is complicated from a security perspective. Every messaging app has its own identifier system: WhatsApp relies on phone numbers, while others like Threema use randomly generated IDs. In connecting an account, that can bring in some level of privacy risk. The integration of BirdyChat, for example, had to meet WhatsApp’s encryption and privacy thresholds before its approval. Meta cautions that while WhatsApp cannot read third-party messages, neither does it control how those partner apps can handle user data, encouraging the user to review each app’s privacy policy.
The interoperability timeline of the DMA is ambitious: the development of one-to-one encrypted messaging must start within three months from the request, group chats have to be supported within two years, and voice or video calls should work within four years. Experts warn that such timelines may be unrealistic considering the technical and policy hurdles. End-to-end encryption protocols must align without introducing vulnerabilities, and mechanisms for preventing spam or scams need to be thought of in a multi-network environment. As Brouwer argues, interoperability “cannot offer the same level of privacy and security” as a closed-network WhatsApp chat, highlighting the trade-offs.
Beyond WhatsApp, the DMA could change messaging architecture throughout the industry. Competitors like Signal, Telegram, and Messenger will have to adjust either their encryption protocols or implement compatibility layers themselves in order to connect with WhatsApp. The aim of the regulation is to reduce” walled gardens”-that is, users will be free to communicate with each other without having to switch apps-but some analysts warn that it may end up further consolidating power if smaller apps integrate into dominant platforms rather than competing on their own.
The beta offers EU-based consumers a first glimpse at a less fragmented messaging future-where contacting friends no longer depends on knowing which app they use. Yet the rollout also serves as a live experiment in balancing interoperability with the uncompromising demands of encrypted communication. As more apps join, the engineering challenge will only grow: aligning disparate cryptographic systems, managing identity across networks, and ensuring that the promise of privacy survives the leap between platforms.
