IPFS CID Version Converter

A CID (Content Identifier) is a self-describing content address used in IPFS and many blockchain systems. It encodes the hash function used, the content type, and the hash itself. Unlike URLs, a CID always refers to the same content regardless of where it's stored — it's content-addressed, not location-addressed.

CIDv0 uses base58btc encoding and always uses SHA2-256 with dag-pb codec. They start with 'Qm'. CIDv1 is more flexible — it supports multiple base encodings (base32, base64, base58), multiple hash functions, and multiple codecs. CIDv1 in base32 starts with 'b'. NFT metadata on Filecoin/IPFS often uses CIDv1 for case-insensitive DNS compatibility.

NFTs store IPFS CIDs as tokenURIs. The token contract returns a URI like `ipfs://QmXxx...` or `ipfs://bafyXxx...`. Marketplaces resolve this by querying an IPFS gateway. The CID is the content hash of the JSON metadata file, which in turn contains image CIDs. This makes NFT metadata tamper-proof.

Multibase is a protocol for encoding binary data as text. The first character indicates the encoding: 'Q' = base58btc (CIDv0), 'b' = base32 (CIDv1), 'z' = base58btc (CIDv1), 'f' = base16 (hex). This allows CIDs and other binary data to declare their own encoding, enabling self-describing identifiers.

Pinning ensures content stays available on the network. Options: (1) Pin locally with `ipfs pin add <CID>`. (2) Use Pinata, Web3.Storage, or NFT.Storage APIs for cloud pinning. (3) Use Filecoin for long-term paid storage. (4) Fleek and similar services offer IPFS+CDN hosting with automatic pinning.