The Protocol Wars: Standards Battle for AI Commerce

Every digital revolution eventually converges on standards. The internet had TCP/IP and HTTP, mobile had iOS and Android, payments had Visa and Mastercard. Now, as the transactional web is reshaped by AI, the battle for standards is playing out between two competing protocols: Agentic Commerce Protocol (ACP) and Agent Payments Protocol (AP2).

This isn’t about who runs the biggest store or has the flashiest assistant. It’s about who defines the rails of AI-native commerce. Whoever wins here will not only capture transaction flow but set the rules for how agents transact across the web.

The Prize: Standard Protocols in AI-Native Commerce

At stake is the ability to mediate trust, interoperability, and scale for AI-driven agents. Payment flows today are fragmented, with merchants relying on platform lock-in or clunky integrations. AI agents, however, require seamless, protocol-level standards: shared tokens for security, platform-agnostic design, and global interoperability.

The winner controls the “Visa/Mastercard layer” of AI commerce—extracting rent from every transaction without owning inventory or consumer interface. The loser risks irrelevance as agents bypass their rails altogether.

Agentic Commerce Protocol (ACP): Open-Source Dominance

Led by OpenAI and Stripe, ACP is designed for speed and openness. Announced on September 29, 2025, and open-sourced from day one, ACP prioritizes adoption over control. Its design mirrors the ethos of the early internet: remove friction, attract developers, and let scale emerge organically.

Strategy:

Open-source to maximize trust and participation.First-mover advantage, announced before Google’s protocol.Platform-agnostic, working across payment processors.

Technical Features:

Shared Payment Tokens (SPT): secure authentication across agents.Works with multiple processors, not just Stripe.1-line integration for Stripe merchants—minimizing onboarding costs.Delegated Payments Spec for non-Stripe merchants, ensuring inclusivity.

Ecosystem Support:

ChatGPT’s 700M weekly users as a built-in adoption engine.Stripe’s 15-year commerce infrastructure and payments network.

ACP’s strength is its simplicity. By positioning itself as a neutral, open protocol, it appeals to early adopters and independent merchants eager to escape walled gardens. For small and mid-sized sellers, ACP feels like a lifeline: fast integration, access to ChatGPT distribution, and a chance to be visible outside Amazon or Google’s ecosystems.

Agent Payments Protocol (AP2): Ecosystem Leverage

Led by Google and PayPal, AP2 plays a different game. Rather than open-source evangelism, it leans on ecosystem leverage: billions of users in Google’s suite and PayPal’s global merchant network. AP2 was announced just two weeks before ACP, a sign that Google knew what was coming and wanted to pre-empt.

Strategy:

Leverage 60+ merchant and institution backers at launch.Integrate natively into Google Shopping and AI Mode in Search.Convert existing relationships into protocol compliance.

Technical Features:

Deep integration with Shopping Graph (50B listings).Real-time inventory sync (2B updates/hour).Google Pay integration across devices.Cross-platform personalization based on Gmail, Maps, and Search data.

Ecosystem Support:

Google AI Mode’s billions of users.PayPal’s 430M+ active accounts across 200 markets.

AP2’s strength is scale and distribution. While ACP courts developers and merchants, AP2 can flip the switch across its existing base. For large retailers who already rely on Google Shopping and PayPal, AP2 feels like a default upgrade, not a new decision.

The Payment Processor Battleground

Behind the protocols lies another war: payment processors jockeying for relevance in an AI-native world.

Stripe is fully aligned with ACP. Its co-development role and 15 years of commerce infrastructure give it credibility.PayPal is embedded in AP2, leveraging its partnership with Google and its 200-market reach. It also powers Perplexity’s checkout, ensuring it plays both sides.Visa entered with Intelligent Commerce (April 2025), striking partnerships with Anthropic, Microsoft, OpenAI, and Perplexity. Unlike Stripe and PayPal, Visa positions itself as a neutral rail, akin to its historical role in credit cards.

The payment processors are hedging. Just as merchants today support both Visa and Mastercard, they may ultimately support both ACP and AP2, leading to fragmentation rather than a clear victor.

Likely Outcome: Fragmentation, Not Monopoly

The most probable outcome is not one protocol defeating the other, but merchants supporting both. History suggests this is the natural equilibrium: just as retailers accept Visa, Mastercard, and Amex, AI commerce may require multi-protocol compatibility.

Yet the consequences of fragmentation are profound:

Merchants bear the cost of dual integrations.Agents must choose which rails to default to, potentially biasing outcomes.Innovation slows as resources are split between protocols.

Still, fragmentation doesn’t mean stasis. Instead, the battle shifts to who captures more volume, faster. If ACP rides ChatGPT’s momentum and Stripe’s ease of integration, it may dominate the long tail of merchants. If AP2 leverages Google’s Shopping Graph and PayPal’s ubiquity, it may consolidate the enterprise tier.

Multi-Protocol Players: The Middle Ground

Some players already embrace multi-protocol hedging. Perplexity, for instance, uses both ACP and AP2. This ensures its “answer engine” can transact regardless of protocol dominance, while keeping leverage against both OpenAI and Google. Visa, too, positions itself as neutral, betting that protocol pluralism is the long-term reality.

For merchants, this strategy is pragmatic. Supporting both protocols ensures reach across agents, while allowing them to hedge against lock-in. The downside: increased integration complexity and reliance on intermediaries to simplify multi-protocol compliance.

The Strategic Clock0–12 months: ACP dominates early adoption thanks to ChatGPT’s scale and Stripe’s simplicity.1–3 years: AP2 closes the gap, leveraging Google’s infrastructure and PayPal’s global network.3+ years: Market fragments, with merchants and agents supporting both. Standardization emerges only through de facto adoption, not through monopoly.

In other words, the protocol wars are a race against the clock. The player that locks in early merchant adoption shapes the trajectory, even if long-term fragmentation prevails.

The Bottom Line

The future of AI commerce won’t be decided by who has the best chatbot, but by who controls the protocol layer. ACP offers openness, speed, and developer goodwill. AP2 offers scale, data, and ecosystem lock-in. Payment processors like Visa and PayPal hedge their bets, ensuring they win regardless of which standard prevails.

The likely outcome: a fragmented landscape where merchants support multiple protocols, just as they accept multiple cards today. But even in fragmentation, volume concentration matters. If ACP captures the long tail and AP2 secures the enterprise, the transactional web may bifurcate.

The strategic takeaway: merchants, agents, and processors must prepare for multi-protocol reality. The prize is too big—AI-native commerce rails will define the next decade of online transactions.

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