Neo co-founder Erik Zhang has added a draft CAIP-2 profile for Neo N3 to the Chain Agnostic namespace registry. The profile defines neo:860833102 as the standardized chain identifier for Neo N3 MainNet, supplying a naming-layer prerequisite for integration with CAIP-2-based systems such as the x402 payment protocol. The identifier has been merged into the Chain Agnostic Standards Alliance registry, though its status remains Draft.
Zhang described the motivation in his announcement:
I started this work after noticing that protocols such as x402 rely on CAIP-2, while native Neo had no canonical identifier. After community discussion and upstream review, the neo namespace and CAIP-2 profile have now been merged into the Chain Agnostic namespace registry. Small piece of infrastructure, but an important prerequisite for wallets, SDKs, payments and multi-chain applications to treat Neo as a first-class network.
What is the CAIP standard?
CAIP stands for Chain Agnostic Improvement Proposals, a collection of specifications published by the Chain Agnostic Standards Alliance. The project aims to do for blockchain interoperability what the Internet Engineering Task Force does for internet protocols: define neutral, multi-stakeholder standards that any chain can implement, without being tied to any single blockchain’s conventions.
The specifications are maintained in two GitHub repositories. The first holds the CAIP specifications themselves. The second holds namespace profiles, one per blockchain family, where chains register their identifiers and document their specific implementations of each CAIP.
CAIP standards cover a range of interoperability problems, from how to identify a chain to how to identify an account on that chain, to how wallets and dApps negotiate capabilities across ecosystems. The key ones relevant to Neo’s registration are:
- CAIP-2: Blockchain ID, the canonical format for identifying any blockchain.
- CAIP-10: Account ID, which extends CAIP-2 to identify wallet addresses in a chain-agnostic way.
- CAIP-19: Asset Type and Asset ID, canonical identifiers for tokens and NFTs across chains.
- CAIP-25: Wallet Create Session JSON-RPC Method, which standardizes how dApps request capabilities and permissions from wallets across different ecosystems.
How does CAIP-2 work?
CAIP-2 defines a simple but consequential format: namespace:reference. The namespace identifies the blockchain family or protocol. The reference identifies the specific network within that family.
Ethereum Mainnet, for example, is eip155:1. The eip155 namespace covers the Ethereum family of chains, and 1 is Ethereum MainNet’s chain ID. Any EVM-compatible chain, including Neo’s own EVM sidechain Neo X, can be identified under the eip155 namespace using its chain ID. Neo N3, which runs its own distinct protocol stack, requires its own namespace.
The reference in neo:860833102 is Neo N3’s network magic number, an integer embedded in the protocol that distinguishes Neo N3 MainNet from other networks at the byte level. The profile notes that network magic values are not guaranteed to be globally unique, as private networks can reuse them, but the value serves as the canonical network discriminator in Neo’s protocol and is the natural choice for the CAIP-2 reference.
Before this registration, there was no agreed-upon, cross-ecosystem way to refer to Neo N3 in chain-agnostic protocols. Multi-chain tools that needed to reference Neo N3 had no standard string to use.
What is x402, and why is CAIP-2 relevant?
x402 is an open HTTP payment protocol built around HTTP status code 402, which the original HTTP specification reserved for “Payment Required.” Originally developed and open-sourced by Coinbase, x402 is now stewarded by the Linux Foundation’s x402 Foundation as of July 2026. It is designed for machine-readable, automated payments, particularly for AI agents that need to pay for API access without human intervention.
The protocol flow works as follows:
- A client sends a request to a paid API endpoint.
- The server responds with a 402 status and a machine-readable payment requirement.
- The client signs a payment authorization and retries the request.
- The server or payment facilitator verifies the authorization and settles the payment on-chain.
The entire exchange is automated and does not require a user-facing payment interface.
x402 uses CAIP-2 identifiers to specify which blockchain and network a payment should be settled on. A payment facilitator built on x402 references chains by their CAIP-2 identifier. Without a registered identifier, a chain is not addressable within that naming layer.
Neo’s neo:860833102 identifier makes Neo N3 referenceable in the CAIP-2 naming system that x402 uses. However, the registration alone does not make Neo N3 operationally supported by x402 facilitators. For Neo to function as an x402 settlement chain, the ecosystem would still need a Neo-specific payment-scheme implementation, client-side transaction signing, server-side verification and settlement logic, and NEP-17 asset support, which is work that remains to be done.
What does the registration enable downstream?
The CAIP-2 registration establishes the identifier layer. The practical implications build on top of it, though each requires its own implementation work.
Multi-chain wallets and SDKs that implement CAIP standards now have a standardized identifier for Neo N3. WalletConnect, for example, uses CAIP-2 and CAIP-25 to establish connections between dApps and wallets across different chains. With a registered Neo namespace, those integrations can reference Neo using a standard string rather than custom naming conventions. However, actual Neo account handling, signing, RPC support, and transaction logic would still need to be implemented for full integration.
The neo namespace also provides the foundation for further CAIP registrations. CAIP-10 account IDs for Neo N3 wallet addresses, CAIP-19 asset identifiers for NEP-17 tokens, and CAIP-25 wallet session interactions can now be developed on top of the established namespace.
CAIP-222 and CAIP-25, currently at Draft and Review status respectively, are the cross-ecosystem analogs of NEP-20, Neo’s wallet authentication standard, and NEP-21, its unified dAPI standard. The CAIP-25 comparison is partial, as CAIP-25 covers session creation while NEP-21 defines a broader dAPI surface. The CAIP-2 registration is the point at which Neo’s internal standards can begin to become legible to that wider ecosystem.
Any protocol, bridge, or application that uses CAIP-2 for chain identification, not only x402, can now reference Neo N3 using a standardized identifier. Chain-specific logic is still required for actual interaction with the network, but the identifier removes the need for custom naming conventions.
The full announcement can be found at the link below:
https://x.com/erikzhang/status/2089902094874775696
