EIP-6969: New ideas for ERC and NFT metadata construction

As NFTs and tokenized assets become increasingly composable and dynamic, metadata has emerged as a bottleneck for scalability, permanence, and interoperability. Today’s metadata practices—most commonly JSON served over HTTP—are fragile, hard to version, and prone to downtime. A new direction informally dubbed “EIP-6969” explores how ERC and NFT metadata could be constructed for the next decade: content‑addressed, verifiable, upgradeable, and chain‑aware by design.

This article outlines a pragmatic architecture for “EIP‑6969‑style” metadata, shows how to implement most of it with existing standards, and explains why this matters in a post‑Cancun world of high‑throughput L2s and modular accounts.

Why metadata needs a rethink

The original NFT standards, including the foundational ERC‑721 and multi‑token ERC‑1155, define a tokenURI that typically resolves to off‑chain JSON. While it’s simple, developers and marketplaces routinely face:

• Fragility and link rot when relying on centralized HTTP endpoints
• Lack of trustworthy versioning and provenance for evolving collections
• Difficulty signaling metadata updates to indexers and UIs
• Inconsistent multi‑chain resolution across L1/L2 ecosystems
• Ambiguous royalty and licensing signals for creators

Several EIPs already address parts of this puzzle. For example, ERC‑4906 adds an event to signal metadata updates to indexers; EIP‑2981 standardizes royalty info; EIP‑3668 (CCIP‑Read) enables trust‑minimized off‑chain reads; and EIP‑1014 (CREATE2) allows deterministic contract addresses for registries and resolvers. Meanwhile, the Ethereum Cancun‑Deneb upgrade (with EIP‑4844) materially improved data availability for L2s, opening the door to more on‑chain or semi‑on‑chain metadata approaches.

What “EIP‑6969‑style” metadata could look like

Think of EIP‑6969 not as a single interface, but as a blueprint combining on‑chain registries, content‑addressed off‑chain data, and strong signaling to wallets and marketplaces.

• Deterministic metadata registries

  • Use CREATE2 to deploy a per‑collection “Metadata Registry” at a predictable address.
  • Registry stores schema commitments, default resolvers, fallback strategies, and version tags.
  • Enables reproducible deployments across chains, reducing ambiguity and spoofing.

• Content‑addressed storage by default

  • Reference metadata by hash rather than a mutable URL; resolve via IPFS content addressing or Arweave Permaweb.
  • Optional HTTP mirrors for performance, but always anchored to a verifiable digest.

• Upgradeable, signaled metadata

  • Emit ERC‑4906 events when token‑level or collection‑level metadata changes, enabling reliable refreshes.
  • Use semantic versioning in the registry to denote schema changes or resolver upgrades.

• Verifiable off‑chain resolution

  • Adopt CCIP‑Read for trust‑minimized off‑chain fetches where data cannot live on‑chain.
  • Sign metadata digests with EIP‑712 typed data; wallets and marketplaces can verify signatures using EIP‑1271 for contract accounts.

• Chain‑aware, multi‑resource URIs

  • Incorporate CAIP‑2 chain identifiers in URIs and registry records to disambiguate L1 vs. L2 variants, consistent with CAIP‑2.
  • Prefer a “multi‑resource” design: primary content address plus optional mirrors (e.g., IPFS CID + HTTPS gateway + Arweave TX).

• Composable schema for NFTs and fungible ERCs

  • Publish JSON Schema or JSON‑LD for trait structure, attributes, and media relations to reduce ambiguity for indexers; see marketplace guidance like OpenSea’s metadata standards.
  • Support role‑aware views (creator vs. holder vs. marketplace) while keeping a single canonical digest per token state.

• Optional account involvement

  • Integrate metadata controls with modular smart accounts through EIP‑6900 (modular accounts) or token‑bound controllers (e.g., EIP‑6551) when creators need programmable policies for updates, licensing gates, or token‑specific logic.

How to build this today with existing EIPs

Until a formal EIP lands, most of the architecture is implementable using proven standards and straightforward patterns:

1. Deploy a Metadata Registry with CREATE2

   • Store:
     • schemaHash (content‑addressed schema)
     • resolver (contract or CCIP endpoint)
     • version (semver string)
     • fallbacks (array of multi‑resource URIs)
   • Interface detection via ERC‑165.

2. Resolve token metadata through CCIP‑Read

   • Onchain method returns a selector instructing the client to fetch off‑chain data from a permitted origin.
   • Off‑chain payload returns metadata plus an EIP‑712 signature; clients verify against either an EOAs’ pubkey or an EIP‑1271 contract.

3. Emit ERC‑4906 events on updates

   • For NFT collections with trait evolutions or dynamic art, trigger MetadataUpdate(tokenId) or BatchMetadataUpdate(fromTokenId, toTokenId).

4. Use content‑addressed URIs everywhere

   • Pin canonical JSON on IPFS or Arweave; embed the CID/TX in registry records.
   • Mirrors can improve latency, but clients should trust the digest.

5. Publish a schema

   • Document attributes, media relations, animation, and editioning in a machine‑readable schema (e.g., JSON Schema) and publish the schema hash to the registry.
   • Align with data fields expected by marketplaces such as OpenSea’s metadata guidance.

6. Royalty and licensing signals

   • Implement EIP‑2981 for royalties, and expose license references as part of the schema to keep legal metadata portable and verifiable.

Design patterns that pay off

• Two‑phase resolution

  • Phase 1: Read on‑chain registry data for version, resolver, and content digest.
  • Phase 2: Perform CCIP‑Read or off‑chain fetch, verify signature against the resolver’s expected signer, and compare digests.

• Multi‑chain consistency

  • Use CAIP‑2 identifiers alongside chain‑specific registry addresses. Marketplaces and wallets can disambiguate which chain variant a token belongs to, improving cross‑chain UX.

• Governance and recovery

  • Registry updates should be controlled by well‑defined policies, ideally via modular accounts (EIP‑6900) or time‑locked roles. Consider staged updates where a new resolver or schema becomes active after a delay.

• Caching and revalidation

  • Clients cache content‑addressed payloads; revalidate on ERC‑4906 events or version changes. This reduces bandwidth while keeping data fresh.

Security considerations

• Trust boundaries

  • Clearly separate the “who can sign metadata” from “who can upgrade resolvers.” Use distinct keys and publish them in‑registry.

• Signature hygiene

  • Prefer EIP‑712 with domain separation, chain IDs, expiry, and nonce to prevent replay and cross‑domain confusion.

• Gateways and mirrors

  • If using HTTPS mirrors, enforce digest checks client‑side. Avoid trusting gateway availability for authenticity; rely on content addressing.

• Backward compatibility

  • Maintain a legacy tokenURI for minimum compatibility, but point to a content‑addressed digest and include registry references for advanced clients.

What this means for users and marketplaces

For collectors, EIP‑6969‑style metadata means fewer broken images, faster refreshes, and clearer provenance. For marketplaces, deterministic registries and strong signaling cut down on off‑chain heuristics, improve indexing accuracy, and reduce disputes over royalties or licenses. For creators, programmable policies become practical: evolve traits post‑mint, branch editions, or gate updates through modular accounts—without sacrificing verifiability.

Standards convergence also helps tooling. Indexers can rely on ERC‑4906 events. Wallets can verify signatures with EIP‑1271. Multi‑chain dapps can align on CAIP‑2 to present coherent cross‑chain collections. And content addressing via IPFS or Arweave keeps the canonical record tamper‑evident.

A 2025‑ready roadmap

• Start migrating collections to content‑addressed URIs and publish a schema hash.
• Add a simple CREATE2 registry contract and emit ERC‑4906 on updates.
• Implement CCIP‑Read for dynamic data that cannot live fully on‑chain; sign payloads with EIP‑712.
• For new mints on L2s, leverage Cancun‑enabled data availability (overview) to store more metadata on‑chain or in blobs, and anchor off‑chain payloads to chain state.
• Explore modular account controls (EIP‑6900) if you need programmable upgrade policies.

Closing thoughts and a practical tip

Even as metadata moves toward verifiable, content‑addressed, and modular designs, one constant remains: signing is the root of trust. Whether you’re a creator publishing a schema change or a marketplace verifying CCIP‑Read payloads, secure EIP‑712 signing and key isolation are essential.

If you prefer a hardware wallet for stronger key security, OneKey provides open‑source firmware, robust secure‑element protection, and smooth support for modern signing flows like EIP‑712 in popular dapps. As metadata architectures increasingly rely on clear, verifiable signatures—especially with CCIP‑Read and contract‑based verification via EIP‑1271—having reliable, auditable signing in your workflow is a practical upgrade for both creators and collectors.

By adopting these “EIP‑6969‑style” patterns today, the ecosystem can make ERC and NFT metadata more durable, interoperable, and future‑proof—ready for the multi‑chain, high‑throughput world that Ethereum and its L2s are steadily delivering.