Deciphr Academy
Track 3 · Module 14 · Lesson 2 of 6 · 6 min read

Where does an NFT's picture actually live?

Short answer

Usually not on the blockchain. Most NFT works are stored off-chain, and the token points to them through a link.1,2 ERC-721 lets that link change, so what an NFT shows depends on who controls the link and the file.2,1

Token #417on the blockchaintokenURIMetadata (JSON)name, description, imageimage linkImage fileon a server or IPFSon-chainusually off-chainIf the link or the file changes, the picture changes
Fig. 2. The token is on the blockchain. Its tokenURI points to a metadata file, and the metadata points to the image.

Three layers

Metadata means information about an NFT, such as its name, a description and its image.2,3 ERC-721 offers an optional add-on for metadata.2

The add-on includes a function called tokenURI. It gives a URI for each token ID.2 A URI is an identifier that points to a particular piece of content, like a web address.4 The tokenURI may point to a text file in a format called JSON.2 JSON is the usual format for NFT metadata.4

So an NFT that uses this add-on has three layers:2

  • The token: its ID and its owner, kept by the contract on the blockchain.3
  • The metadata: a JSON file, found through the tokenURI, with a name, a description and an image link.2
  • The image: a file, found through the "image" link in the metadata.2

Why most pictures live off the chain

The ERC-721 authors considered putting all metadata on the blockchain. They rejected it as too expensive.2 ethereum.org says storing large amounts of data on Ethereum would be prohibitively expensive, because of gas fees.5

"On-chain" storage means the work is kept on the blockchain itself. "Off-chain" storage means it is kept somewhere else, and the token points to it.1 In 2024, the US Patent and Trademark Office and Copyright Office reported on NFTs. They found that the vast majority of NFT works are stored off-chain.1

Off-chain storage can be a central server reached by a normal web address. It can also be a decentralised network such as IPFS.1

Links can change

ERC-721 says the tokenURI may change from time to time.2 The authors had in mind an NFT for a house, whose details naturally change.2

That cuts both ways. The US report quotes a study: with a normal server, an NFT's creator can freely change or remove the image file.1

Content addressing with IPFS

IPFS finds files by what is in them, not by where they are. Its content identifier, or CID, is an address made from the content itself.6 Any change to the content produces a different CID.6 So an IPFS link can't be altered to point at different data once it is made.4

But IPFS does not keep files forever on its own. Copies held by computers on the network are temporary, and get deleted unless someone "pins" them.4 Pinning tells an IPFS computer to keep the data.7 Pinning services keep data for a fee, but IPFS warns there is no guarantee they will keep running.7 ethereum.org adds that IPFS has no built-in reward for storing data.5

A gateway is a website that fetches IPFS content over the normal web. The IPFS docs warn that a gateway link can fail if its operator goes offline.4

Kind of link What it points to Main weakness
Normal web address A file on one party's server1 The file can be changed or removed1
IPFS link (ipfs://) The content itself, by its CID6,4 Lost if nobody keeps a pinned copy4
Gateway link IPFS content, through one website4 Fails if that website goes offline4
Our viewBefore you put a value on an NFT, follow its links. If the picture sits on one company's server, you are trusting that company to keep it there, unchanged.
Next

The next lesson covers how NFTs are created, and where they are bought and sold.

WatchNFTs in about two minutes. Captions are built in. Sources are listed at the end.
Sources
  1. Non-Fungible Tokens and Intellectual Property: A Report to Congress. US Patent and Trademark Office and US Copyright Office, March 2024.
  2. ERC-721: Non-Fungible Token Standard. Ethereum Improvement Proposals (Entriken, Shirley, Evans and Sachs), created 24 January 2018.
  3. Non-fungible tokens (NFT). ethereum.org, updated 23 June 2026.
  4. Best practices for storing NFT data using IPFS. IPFS Docs, checked 22 October 2026.
  5. Decentralized storage. ethereum.org developer docs, updated 13 May 2026.
  6. Content Identifiers (CIDs). IPFS Docs, checked 22 October 2026.
  7. Persistence, permanence, and pinning. IPFS Docs, checked 22 October 2026.
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General education built from the publicly available sources listed above. Not financial, legal, tax or investment advice. Naming a company, project or regulator is not an endorsement either way. Last checked 2026-10-22. Terms and disclaimer.