Neynar Documentation

A user can change their offchain ENS name or Fname without affecting their account’s history. This can be done at most once in 28 days.

Fnames may be revoked if you violate the usage policy.
Apps may lower your reputation if you change Fnames often.

Requirements

An ETH wallet that owns the account on OP Mainnet. No ETH is required.

Change username

To transfer an Fname, e.g. farcaster, make a POST request to /transfers with the following body:

{
  "name": "farcaster", // Name to transfer
  "from": 123,  // FID to transfer from
  "to": 321, // FID to transfer to
  "fid": 123, // FID making the request (must match from)
  "owner": "0x...", // Custody address of FID making the request
  "timestamp": 1641234567,  // Current timestamp in seconds
  "signature": "0x..."  // EIP-712 signature signed by the custody address of the FID
}

To generate the EIP-712 signature, use the following code:

import { makeUserNameProofClaim, EIP712Signer } from '@farcaster/hub-nodejs';

const accountKey: EIP712Signer = undefined; // Account Key for the custody address (use appropriate subclass from hub-nodejs for ethers or viem)

const claim = makeUserNameProofClaim({
  name: 'farcaster',
  owner: '0x...',
  timestamp: Math.floor(Date.now() / 1000),
});
const signature = (
  await accountKey.signUserNameProofClaim(claim)
)._unsafeUnwrap();

Example request via curl:

curl -X POST https://fnames.farcaster.xyz/transfers \
  -H "Content-Type: application/json" \
  -d \
'{"name": "farcaster", "owner": "0x...", "signature": "0x...", "from": 123, "to": 321, "timestamp": 1641234567, "fid": 123}'

See here for more details on the Fname registry API.