The picture shown beside an ERC-721 NFT can depend on a link supplied by its metadata. The standard allows that link to change. Buying the token therefore does not, by itself, establish that the same picture will remain accessible at the same address.
| What you need to know |
|---|
| ERC-721 defines its metadata extension as optional. |
| The extension's tokenURI method can point to a JSON metadata file. |
| The standard permits the metadata URI to change over time. |
| IPFS does not guarantee that stored content remains persistently available. |
The ERC-721 specification separates the token’s ownership functions from its optional metadata extension. A token can comply with the core standard without offering that extension. Where the extension is implemented, tokenURI supplies an address for information about the asset; the proposed JSON schema includes an image field containing another address.
That creates two links worth distinguishing when examining a particular collectible: the address returned by the contract, and the image address inside the metadata. Finding the first does not establish where the picture itself is stored. It may lead to a metadata file which, in turn, points elsewhere for the image.
The standard expressly permits a mutable metadata URI. It gives a house as an example of an asset whose image and other details can naturally change. Mutability is consequently compatible with ERC-721; it is not, on its own, proof that a collection has broken the standard or that an attacker has acted.
Whether a particular collection allows updates depends on its implementation. A claim that its pictures are fixed needs evidence about that collection’s contract and storage arrangement. The ERC-721 label alone cannot settle it. This guide compares the specification with storage documentation; it does not claim to have tested a collection’s controls.
IPFS still needs someone to retain the files
Moving the files to IPFS does not remove the storage question. The official IPFS persistence documentation explains that nodes can discard cached resources during garbage collection. Pinning protects data against that process on the node retaining it.
There must still be a willing storage provider. The documentation warns that content may be lost entirely if its only sponsor stops paying for pinning, and says IPFS does not guarantee persistent availability. For an NFT whose metadata and image are separate files, the useful storage question covers both. Keeping the metadata available would not alone establish that its separately linked picture is also retained.
