Why your messaging apps don't talk to each other (and what we'd gain if they did)

Bottom line up front: federated messaging systems could eliminate the frustrating need to maintain multiple messaging apps whilst preserving user choice and innovation. However, the transition requires overcoming significant network effects, addressing complex technical challenges, and ensuring that enhanced connectivity doesn't come at the cost of user experience simplicity.

Every day, billions of people juggle multiple messaging applications—WhatsApp for family, Slack for work, Discord for gaming, and Signal for privacy-conscious conversations. This fragmentation forces users into digital silos where communication depends entirely on platform adoption by their contacts. Yet this wasn't always the inevitable way of digital communication.

Email offers a compelling counter-narrative: a successful federated system where users with completely different service providers can seamlessly communicate. Someone using Gmail can effortlessly send messages to recipients on Outlook, ProtonMail, or any other email service. This interoperability exists because email built its foundation on open standards, specifically the Simple Mail Transfer Protocol (SMTP), rather than proprietary, closed systems.^[1]

The question facing modern communication is whether messaging platforms can achieve similar federation without sacrificing the user experience that makes current platforms successful.

Email's blueprint for federation

Email's evolution provides crucial insights into how communication federation works in practice. In the 1980s and early 1990s, corporate email systems operated as isolated islands.Few large companies (notably IBM, DEC, and Control Data) built corporate email systems for large-company use, and none of these systems provided much in the way of interoperability.^[1:1] Users within different organisations couldn't communicate electronically, creating the same silos we see today with messaging platforms.

The transformation began when Jonathan Postel published RFC821 in early August 1982 detailing the SMTP protocol, followed by David Crocker's RFC822 which detailed how messages could be transmitted over Internet-capable networks.^[2] However, adoption wasn't immediate. The difficulty of getting interoperability to reliably work across multiple MTA vendors and their individual connectors put a lot of market pressure on vendors to come up with a simpler, more robust solution, so native SMTP began to gather real momentum in the mid-1990s.^[1:2]

The success of email federation demonstrates several key principles that enabled universal adoption.

• Open standards enable universal compatibility: SMTP's standardisation allowed any email provider to communicate with any other, regardless of underlying infrastructure
• Market pressure drives adoption: Vendor frustration with proprietary connectors accelerated the move towards open protocols
• Federation preserves choice: Users can select email providers based on features, privacy policies, or pricing whilst maintaining universal connectivity

The current messaging landscape: walled gardens and network effects

Today's messaging platforms operate as modern fiefdoms, each controlling access to their user base. Those looking to embrace independent privacy-focused messaging apps such as Signal will hit a brick wall when they realise that all their buddies are using WhatsApp. Or iMessage. Or Telegram. Or Viber.^[3]

This fragmentation isn't accidental—it's the result of powerful network effects that create competitive moats. According to Economics for Managers, the underlying principles of network effects imply that the business, website, or platform with the highest market share will be more successful in the long run.^[4] Each platform benefits when users feel locked into their service because their social or professional networks exist there.

The mechanics of messaging network effects create particularly strong barriers to switching platforms.

Direct network effects: A user is more likely to choose WhatsApp over a new app simply because it's where their social circle is already active. The established network of users creates a gravitational pull, attracting more users and reinforcing its dominance.^[5]

Switching costs: Moving to a new platform means convincing your entire network to follow. If a developer wants to launch a new messenger application, their product's added value must be strong enough to not only convince new users to switch but also motivate them to persuade their own contacts to join the app.^[5:1]

Multi-tenanting limitations: Unlike other digital services where users easily maintain multiple accounts, messaging apps face pressure when users are unable to use a single platform to accomplish their goals, leading to fragmented conversations across platforms.^[6]

Regulatory intervention: the Digital Markets Act as a catalyst

Recognition of these problems has prompted regulatory action. The European Union's Digital Markets Act (DMA) represents the most significant attempt to force messaging interoperability. One of its requirements is that designated messaging services must let third-party messaging services become interoperable, provided the third-party meets a series of eligibility, including technical and security requirements.^[7]

Currently, the only messaging services considered a DMA Gatekeeper are WhatsApp and Facebook Messenger. Unfortunately Apple has wriggled out of their obligation so far, by claiming that iMessage has insufficient use in the EU to qualify.^[8]

Meta's response reveals both the potential and limitations of forced interoperability. Meta now says it will ask third parties to use the Signal protocol, though it may make exceptions to this in the future.^[9] However, Meta hedges on this a bit by saying that, although it has built a secure solution using the Signal protocol to protect messages in transit, it can't guarantee "what a third-party provider does with sent or received messages".^[9:1]

User experience gains from federated messaging

Federation could transform the user experience by addressing several frustrations that users currently face with fragmented messaging platforms.

Simplified communication management

Users could maintain a single messaging application whilst communicating with contacts across any platform. This eliminates the cognitive overhead of remembering which platform each contact prefers and reduces the notification chaos of managing multiple messaging apps.

Enhanced network freedom

The whole idea is to figure out a practical way in which WhatsApp could interoperate with iMessage, Google Messages and others, creating an interoperable communication network where users are no longer locked into communication silos and pick their preferred service provider without compromising on who they can talk to.^[10]

Users could choose messaging providers based on their specific priorities (privacy, features, cost, or user interface) without sacrificing connectivity to their social and professional networks.

Competitive innovation

Federation could accelerate innovation by removing network effects as the primary competitive advantage. Platforms would need to compete on user experience, features, and service quality rather than simply user base size. This mirrors how email providers differentiate themselves through storage capacity, spam filtering, user interfaces, and additional features whilst maintaining universal compatibility.

Reduced switching costs

Moving between messaging providers becomes significantly easier when users don't need to convince their entire network to migrate. This promotes healthy competition and prevents platforms from becoming complacent about user experience.

Potential user experience compromises

However, federation introduces complexities that could compromise the streamlined experience users currently enjoy.

Feature fragmentation

Different platforms offer varying capabilities—voice messages, file sharing limits, encryption standards, or reaction emoji. Federation requires handling the "lowest common denominator" problem where advanced features may not work across all platforms.

Current messaging apps optimise their entire experience around platform-specific capabilities. Meta is going beyond basic interoperability. In addition to enabling basic messaging functions, it plans to support richer features such as message reactions, direct replies, typing indicators, and read receipts.^[7:1] However, these enhanced features may not translate across federated connections.

Identity and privacy complexity

Federation introduces questions about data handling, encryption standards, and user consent that could overwhelm users with complex privacy decisions. At the DMA stakeholder workshop on messaging interoperability, participants debated whether users would need to consent or opt-in/opt-out of interoperability, highlighting the various data privacy implications that federation introduces.^[10:1]

Reliability and performance variations

Users currently expect consistent performance within platforms. Federation introduces variables in message delivery, encryption, and feature availability depending on the recipient's platform, potentially creating unpredictable user experiences.

Interface complexity

Managing cross-platform communication may require interface elements that indicate platform compatibility, feature availability, and security levels—adding complexity to currently streamlined interfaces.

Technical approaches to federation

Several technical models are emerging for federated messaging, each with different implications for user experience and implementation complexity.

Client-side bridging

Element has successfully integrated 1:1 chats between Matrix and WhatsApp via the DMA APIs, while maintaining end-to-end encryption (having implemented full Signal compatibility in vodozemac).^[8:1] This approach allows existing platforms to communicate through technical bridges whilst maintaining their native interfaces.

Protocol standardisation

Matrix aims to make real-time communication work seamlessly between different service providers, in the way that standard Simple Mail Transfer Protocol email currently does for store-and-forward email service.^[11] This approach requires platforms to adopt common protocols, similar to how email uses SMTP.

Platform APIs

The DMA approach requires dominant platforms to open APIs for third-party integration. Meta's messaging app users, particularly WhatsApp users, who have had E2EE on by default for years, want to know that their conversations will remain secure, despite the DMA's changes.^[9:2]

Real-world federation examples

Several federated communication systems already demonstrate practical implementation across different use cases and scales.

Matrix protocol adoption: Germany's national healthcare system's internal communication network uses a Matrix-based system (Ti-Messenger) for real-time communication among Germany's healthcare organisations and sharing of sensitive patient data.^[11:1] This shows federation working at enterprise scale with stringent security requirements.

ActivityPub ecosystem: The Fediverse is a collection of social networking services that can communicate with each other using a common protocol. Users of different websites can send and receive status updates, multimedia files and other data across the network. Platforms like Mastodon demonstrate federation working for social media communication.

Email's continued evolution: Email remains the most successful federated communication system, handling over 100 billion messages daily across countless providers whilst maintaining universal compatibility.^[7:2]

The path forward: lessons from email

Email's federation success offers a roadmap for messaging platforms. The key lessons include several crucial steps that could guide modern implementation.

1. Start with basic interoperability: Email began with simple text messaging before adding features like attachments, HTML formatting, and enhanced security.

2. Evolve standards gradually: SMTP has evolved through multiple RFC updates whilst maintaining backward compatibility.

3. Address security incrementally: Email added encryption, authentication, and spam filtering as overlay protocols rather than rebuilding the foundation.

4. Preserve user choice: Email federation succeeded because it enhanced rather than restricted user options.

The key insight is that federation doesn't require perfection from day one. Interoperability is an important tool to promote competition and prevent monopolists from shutting down user-empowering innovation.^[12] Even imperfect federation can provide substantial user benefits whilst protocols and implementations improve over time.

Looking ahead: the user experience equation

The success of federated messaging will ultimately depend on whether it can enhance user experience rather than complicate it. Email succeeded because it solved a fundamental problem, enabling communication across organisational boundaries, whilst remaining simple for end users.

Modern messaging federation faces a more complex challenge: competing against platforms that have already achieved excellent user experiences within their silos. The value proposition must be compelling enough to overcome the inertia of existing network effects whilst delivering tangible benefits that users can immediately perceive.^[13]

The early implementations emerging through regulatory pressure and open-source initiatives will serve as crucial testing grounds. Their success or failure in maintaining user experience whilst enabling cross-platform communication will determine whether federated messaging becomes the future of digital communication or remains a technical curiosity.

For users, the promise is significant: true communication freedom where platform choice is based on personal preferences rather than network constraints. The challenge lies in achieving this vision without sacrificing the simplicity and reliability that make current messaging platforms indispensable tools for billions of people worldwide.

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