NFT Metadata Validator

WHAT IT DOES

The NFT Metadata Validator reads NFT token URIs from ERC‑721 and ERC‑1155 contracts via tokenURI() or uri(), fetches the metadata JSON from IPFS or HTTPS gateways, and validates the schema—checking for required fields like name, image, and description, and listing attributes if present. It also shows the raw URI and highlights potential issues such as missing fields or IPFS gateway dependencies. This gives you a clear view of what the NFT actually points to, helping you spot broken metadata, misconfigured tokens, or assets that may not render correctly in wallets or marketplaces.

HOW TO USE

1. Connect your EVM wallet (optional—the tool works without it).

2. Select your chain: Ethereum (1), Polygon (137), or Arbitrum (42161).

3. Enter the NFT collection contract address and the token ID you want to validate.

4. Click "Fetch metadata".

5. Review the results: the tool shows the token standard, raw URI, parsed metadata, a schema validation summary, and any errors encountered.

THE REAL MECHANISM — on‑chain URI resolution with off‑chain JSON validation

This tool performs a two‑step validation process. First, it calls the contract’s tokenURI() function for ERC‑721 or uri() for ERC‑1155 via eth_call to retrieve the raw metadata URI. The URI may be an IPFS URI (ipfs://) or an HTTPS URL. Second, it fetches the metadata JSON using GM_xmlhttpRequest, which supports cross‑origin requests in the BotGentz sandbox. The tool then validates the JSON structure against the expected NFT metadata schema, checking for the presence of name, image, description, and attributes. It also identifies IPFS URIs and alerts the user that a public gateway is needed to view the image. All validation happens client‑side—no metadata is stored or transmitted beyond the fetch request.

WHAT IT CANNOT SEE

- This tool cannot validate metadata for tokens that use non‑standard tokenURI() implementations that don't return a valid URI.

- It cannot fetch metadata from IPFS gateways that are down or rate‑limited.

- It cannot verify the authenticity or "rarity" of NFT metadata beyond validating the format.

- It cannot detect metadata that is stored off‑chain and has been modified after minting without on‑chain verification.

- It cannot check if an image URL points to a valid image file without attempting to fetch it.

- It cannot verify on‑chain ownership or transfer history.

PLEASE NOTE

- This tool works on Ethereum (1), Polygon (137), and Arbitrum (42161).

- The tool is read‑only—it never submits transactions or modifies chain state.

- Metadata fetched from IPFS depends on gateway availability; if an IPFS URI fails, try using a public gateway like ipfs.io or cloudflare-ipfs.com.

- The tool does not validate the actual image file content—only the metadata JSON structure.

- The collection contract must support the standard tokenURI() (ERC‑721) or uri() (ERC‑1155) function for the tool to work.