Why Messaging Apps Still Struggle With True Interoperability

Fact-checked by the SnapMessages editorial team

Updated July 2026

Messaging app interoperability, the ability to send messages across different platforms without switching apps, has been a persistent technical and political failure for over a decade. According to Statista’s global messaging data, the top five messaging platforms collectively serve more than 5 billion monthly active users, yet none of them communicate natively with each other.

This matters now because regulators in the EU and UK are pushing harder than ever for open standards. The technical reality is proving far more complicated than any single law can fix. WhatsApp’s own engineering leadership has said as much in public: opening the platform to outside clients means renegotiating the trade-off between openness and the security guarantees users already expect.

What Is Messaging App Interoperability and Why Does It Still Not Exist?

Messaging app interoperability means a user on WhatsApp can message someone on Signal or Telegram without either party downloading a new app. It does not exist at scale today because each platform was built on proprietary protocols designed to lock users in, not to connect outward.

WhatsApp uses its own implementation of the Signal Protocol. iMessage runs on Apple Push Notification Service infrastructure that is deliberately closed. Telegram uses its custom MTProto encryption. These are not just different roads. They are different transportation systems entirely. Bridging them requires agreement on a shared protocol, and no dominant platform has a financial incentive to make switching easier for its users.

The closest the industry has come to a universal standard is Matrix, an open-source protocol maintained by the non-profit Matrix.org Foundation. Matrix supports federated, encrypted messaging across servers, but adoption among mainstream consumer apps remains minimal. If you want to understand how cross-platform communication works at a lower level today, our breakdown of how cross-platform messaging works between iPhone and Android covers the current infrastructure clearly.

What Does the EU Digital Markets Act Actually Require From Messaging Platforms?

The EU’s Digital Markets Act (DMA) is the most significant regulatory intervention in messaging history. It requires designated “gatekeepers”, platforms with over 45 million EU monthly users and a market cap above 75 billion euros, to open their messaging infrastructure to third-party interoperability upon request. The structure echoes how financial regulators like the CFPB or the Federal Reserve impose disclosure and access rules on large banks such as Chase or Wells Fargo once they cross a systemic-importance threshold: size alone triggers obligations that smaller competitors never face.

Meta, Apple, and Google were designated as gatekeepers under the DMA in 2023. The first interoperability obligations for one-to-one messaging took effect in March 2024, according to the European Commission’s DMA enforcement page. Group messaging and voice/video call interoperability carry later deadlines, 2025 and 2027 respectively.

How Are Platforms Responding to DMA Mandates?

Meta announced a third-party interoperability API for WhatsApp in 2024. However, critics including the Electronic Frontier Foundation have flagged that the implementation terms allow Meta to set conditions that could make integration technically burdensome for smaller rivals. Apple’s iMessage, classified under a different gatekeeper category, initially argued it should be exempt, a position the European Commission rejected.

Compliance has been slow and partial. The DMA does not specify which technical protocol platforms must use, only that they must enable interoperability. That ambiguity gives gatekeepers wide latitude to propose solutions that technically comply but practically obstruct competition. BEREC, the body of European telecom regulators, weighed in directly on this problem: its opinion on Meta’s reference offers for Messenger and WhatsApp interoperability under DMA Article 7 lays out the technical requirements Meta must meet, with particular attention to end-to-end encryption and compliance timelines. That opinion is one of the clearest signals yet that regulators, not just Meta, recognize how much room the current rules leave for foot-dragging.

Dick Brouwer, an engineering director at WhatsApp, has been candid about the underlying dilemma. “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,” he said. Brouwer has also emphasized that any bridge WhatsApp builds will be opt-in rather than automatic: “One of the core requirements here, and this is really important, is for users for this to be opt-in.”

Why Does End-to-End Encryption Make Interoperability So Technically Hard?

End-to-end encryption is the single biggest technical barrier to messaging app interoperability. When encryption keys are generated and stored on user devices, bridging two platforms means agreeing on how each system handles key exchange, verification, and forward secrecy, and that agreement is extraordinarily difficult to achieve without weakening security.

Signal’s protocol, widely regarded as the gold standard, uses Double Ratchet encryption combined with X3DH key agreement. WhatsApp licensed this protocol but implemented it in a closed environment. If WhatsApp were to accept messages from an outside platform, it would need to verify that the outside platform’s key management is equally trustworthy. There is currently no audited, universally accepted standard for cross-platform key federation. WhatsApp’s Brouwer has said the company’s preferred path keeps its existing architecture intact rather than building a parallel system from scratch: “We think that the best way to deliver this approach is through a solution that is built on WhatsApp’s existing client-server architecture.”

Not everyone is convinced that approach solves the underlying power problem. Carmela Troncoso, an associate professor focusing on security and privacy engineering at École Polytechnique Fédérale de Lausanne (EPFL), has pointed out a paradox in how these mandates play out in practice: “This move for interoperability will, on the one hand, open the market, but also maybe close the market in the sense that now the bigger players are going to have more decisional power.”

This is why security researchers warn that forced interoperability, if poorly implemented, could create new attack surfaces. A compromised third-party client could be used to intercept messages that were presumed secure. Understanding these risks is especially important for users who already think carefully about securing their messaging apps before international travel.

Consider a reader who splits time between a personal WhatsApp account and a work Signal account, and who travels for business roughly six times a year. If a poorly vetted interoperability bridge were switched on by default rather than opt-in, that person’s exposure would double instantly: two encrypted inboxes instead of one, connected through a link neither app’s engineers fully control. That is the practical reason WhatsApp keeps insisting the feature stays opt-in rather than automatic. One compromised bridge affects every conversation routed through it, not just a single message.

How Do Major Messaging Platforms Compare on Interoperability Readiness?

Not all platforms are equally resistant to interoperability. Open-protocol apps like Element (built on Matrix) and XMPP-based clients are already interoperable by design. The problem is that they hold a tiny fraction of global users compared to closed giants.

RCS (Rich Communication Services) represents one partial success story, and the money behind it makes the trajectory clear. Global operator revenue from RCS messaging was $1.3 billion in 2023, and Juniper Research projects that figure will reach $8 billion by 2025, a roughly sixfold jump in two years, according to Juniper Research (2024). That same research projects the RCS active subscriber base will grow by 900 million over two years to reach 2.1 billion globally, largely on the back of Apple’s adoption of the standard. Still, RCS remains behind other messaging formats in raw reach: OTT business messaging channels counted 4.1 billion global users in 2024, compared to RCS’s 1.2 billion, per the same Juniper data.

France offers a useful national case study on how fast RCS coverage can move once carriers commit to it. By the end of 2025, the country had 50 million RCS-compatible smartphones in use, up 76.6% from the year before, and national RCS coverage reached 83% by the fourth quarter of 2025, according to AF2M (2026). That is a fast rollout for a standard that spent most of the past decade stuck in pilot programs. It is also a reminder that carrier-level interoperability can scale quickly once the incentives align, even while app-level interoperability among WhatsApp, iMessage, and Telegram stays frozen. Apple adopted RCS on iPhones in 2024 after years of resistance, enabling richer cross-platform messaging between iPhone and Android users. However, RCS encryption is not end-to-end by default across all carriers, a significant limitation. Our detailed coverage of how RCS is replacing traditional texting on iPhones explains what changed and what still falls short.

What Business Incentives Are Actively Blocking Messaging Interoperability?

Business model lock-in is as powerful a barrier as any technical limitation. Each major platform profits from keeping users inside its ecosystem. WhatsApp drives Meta’s advertising and payments strategy. iMessage is a key differentiator in Apple’s premium device ecosystem. Telegram monetizes through premium subscriptions tied to its proprietary feature set.

Opening up to interoperability reduces switching costs, the friction that keeps users from moving to a competitor. Lower switching costs mean lower user retention, which directly threatens platform revenue. This is why interoperability mandates face intense lobbying: the financial stakes are measured in billions of dollars of ecosystem value, not just messaging feature parity. It’s a dynamic not unlike how banks such as SoFi or Chase resist open banking rules pushed by the CFPB, since portable account data lowers the cost of a customer walking away, the same way a FICO Score follows a borrower from one lender to the next regardless of who originated the loan.

The network effect compounds this. A platform with 2 billion users like WhatsApp is more valuable precisely because everyone is already there. Interoperability would neutralize that advantage, allowing a small secure app to communicate with WhatsApp’s entire user base without offering WhatsApp anything in return. Understanding how AI features are now being woven into this closed ecosystem dynamic is also worth tracking, see our analysis of how AI is being used inside messaging apps right now.

There is also a security accountability problem. If a third-party app sends a malicious message through an interoperability bridge, who is liable, the originating platform or the receiving one? No regulatory framework has clearly resolved this yet, giving platforms additional cover to resist compliance. It’s a gap similar to disputes the FDIC and Federal Reserve have had to referee between banks over fraud liability on shared payment rails, where the party at fault often isn’t obvious until well after the damage is done.

Related reading: Pro Techniques for Detecting Phishing Messages in Messaging Apps.

Frequently Asked Questions

Can I already send messages from WhatsApp to Signal in 2026?

No. Direct messaging between WhatsApp and Signal is not possible for general users. WhatsApp has published a limited interoperability API for EU-based third-party developers under DMA obligations, but no consumer-facing cross-platform chat between these two apps exists yet.

What is the Digital Markets Act and how does it affect messaging apps?

The Digital Markets Act is EU legislation that designates large tech platforms as “gatekeepers” and imposes interoperability requirements on their messaging services. Platforms with over 45 million EU monthly users must allow third-party apps to connect to their messaging infrastructure upon request. Enforcement began in March 2024.

Does RCS solve the messaging interoperability problem?

RCS solves carrier-level interoperability, not app-level interoperability. Android and iPhone users can now exchange RCS messages with richer features than SMS, but end-to-end encryption under RCS is not universally implemented across all carriers and devices.

Why does end-to-end encryption make cross-platform messaging harder?

End-to-end encryption requires both platforms to agree on how encryption keys are generated, stored, and verified. When platforms use different protocols, like Signal Protocol versus MTProto, bridging them without compromising security requires a trusted intermediary layer that does not yet exist at scale.

Which messaging app is most open to interoperability right now?

Element, built on the open Matrix protocol, is the most interoperable mainstream messaging app available today. It can federate with any other Matrix-compatible server. XMPP-based clients also support interoperability, though both have significantly smaller user bases than WhatsApp or iMessage.

Is messaging app interoperability a privacy risk?

It can be, if implemented poorly. A compromised or lower-security third-party client connecting via an interoperability bridge could expose messages that users assumed were fully encrypted. Security experts including those at the Signal Foundation recommend that any interoperability standard must mandate equivalent encryption and key verification requirements on all connected platforms. For broader context, understanding how to build a personal digital security routine helps users make informed choices regardless of which platform they use.

Will WhatsApp interoperability be mandatory for users, or opt-in?

Opt-in. WhatsApp’s own engineering leadership has stated that users must actively choose to enable cross-platform messaging rather than having it switched on by default, a design decision meant to limit exposure to unvetted third-party clients.

What does BEREC’s opinion on WhatsApp interoperability actually cover?

BEREC’s opinion evaluates the technical terms Meta proposed for opening Messenger and WhatsApp to third parties under DMA Article 7. It focuses on whether Meta’s reference offers preserve end-to-end encryption, meet reasonable compliance timelines, and avoid placing undue technical burden on smaller developers trying to connect.

Does iMessage have to become interoperable with Android messaging apps?

Apple’s iMessage remains under regulatory review rather than a finalized interoperability mandate. Apple initially argued for an exemption from DMA gatekeeper obligations, a position the European Commission rejected, and the matter remains an area of ongoing scrutiny rather than settled compliance.

Why haven’t Telegram or Signal been designated as DMA gatekeepers?

Neither platform has crossed the DMA’s threshold of over 45 million monthly EU users combined with a market capitalization above 75 billion euros. Because gatekeeper status triggers the interoperability obligation, smaller platforms like Telegram and Signal currently have no legal requirement to open their messaging infrastructure.