NEP-330: Contract source metadata

A deployed NEAR contract is just Wasm bytes. NEP-330 adds one view method, contract_source_metadata(), that tells anyone where the source lives, which version is deployed, which standards it implements, and how to rebuild it — so the Wasm can be checked against the source.

All fields are optional, but the more you fill in, the more useful the contract is to explorers, wallets and auditors.

What contract_source_metadata returns (shape from the NEP, values illustrative)

JSON

{
  "version": "1.0.0",
  "link": "https://github.com/example/my-token/tree/9c16aaff3c0fe5bda4d8ffb418c4bb2b535eb420",
  "standards": [
    { "standard": "nep330", "version": "1.3.0" },
    { "standard": "nep141", "version": "1.0.0" },
    { "standard": "nep145", "version": "1.0.0" },
    { "standard": "nep148", "version": "1.0.0" }
  ],
  "build_info": {
    "build_environment": "sourcescan/cargo-near:0.x.y-rust-1.xx.0@sha256:<digest>",
    "source_code_snapshot": "git+https://github.com/example/my-token?rev=9c16aaff3c0fe5bda4d8ffb418c4bb2b535eb420",
    "contract_path": "",
    "build_command": ["cargo", "near", "build", "non-reproducible-wasm", "--locked"],
    "output_wasm_path": "/home/near/code/target/near/my_token.wasm"
  }
}

Field	Meaning
`version`	Version or commit of the deployed code.
`link`	Where to find the source (repository URL or IPFS CID).
`standards`	List of `{ standard, version }` the contract claims to implement, e.g. `nep141` `1.0.0`.
`build_info.build_environment`	The Docker image (pinned by digest) the Wasm was built in.
`build_info.source_code_snapshot`	Exact source reference, e.g. a git URL with the commit `rev`.
`build_info.contract_path`	Path of the contract crate inside that repository (empty for the root).
`build_info.build_command`	The exact command, as an array of arguments, run inside the image.
`build_info.output_wasm_path`	Where that command writes the Wasm inside the image.

Adding it with near-sdk#

ERC-165 interface detection vs NEP-330 standards list

Solidity

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;

import {ERC165} from "@openzeppelin/contracts/utils/introspection/ERC165.sol";
import {IERC721} from "@openzeppelin/contracts/token/ERC721/IERC721.sol";

// ERC-165: ask "do you support interface id X?" one id at a time.
// Source verification (Etherscan etc.) happens off-chain.
abstract contract MyNft is ERC165 {
    function supportsInterface(bytes4 id) public view virtual override returns (bool) {
        return id == type(IERC721).interfaceId || super.supportsInterface(id);
    }
}

Rust

use near_sdk::near;

// near-sdk generates the contract_source_metadata() view.
// version / link default to NEP330_VERSION / NEP330_LINK env vars,
// falling back to the crate's Cargo.toml version and repository.
#[near(contract_state, contract_metadata(
    version = "1.0.0",
    link = "https://github.com/example/my-nft",
    standard(standard = "nep171", version = "1.0.0"),
    standard(standard = "nep181", version = "1.0.0"),
))]
#[derive(Default)]
pub struct Contract {}

Coming from EVM

supportsInterface(id) ↔ the standards array: one call returns every standard (with version) the contract claims.

NEP-330 also carries what Etherscan-style verification needs (source snapshot, build image, command), but on-chain and in a standard shape, so anyone can re-run the build.

Adding it with near-sdk#

Check yourself