Farcaster by Ethereum address

Reverse-lookup an Ethereum address to its Farcaster account (via verified address). Returns FID, username, display name, bio, follower/following counts, and Warpcast URL, or found=false if the address has not verified on Farcaster. Use to label wallet activity with the owner's Farcaster identity when ENS is missing.

Input

Example output

{
  "found": true,
  "address": "0xd7029bdea1c17493893aafe29aad69ef892b8ff2",
  "fid": 3,
  "username": "dwr",
  "displayName": "Dan Romero",
  "pfpUrl": "https://...",
  "bio": "Working on Farcaster.",
  "followerCount": 500000,
  "followingCount": 1000,
  "venueUrl": "https://warpcast.com/dwr",
  "source": "neynar"
}

Try it - see the 402 challenge (free)

curl -i -X POST https://agent402.tools/api/farcaster-by-address \
  -H "Content-Type: application/json" \
  -d '{"address":"0xd7029bdea1c17493893aafe29aad69ef892b8ff2"}'

The response is HTTP 402 Payment Required with exact payment requirements. Any x402 v2 client pays automatically and retries:

Paid call (JavaScript agent)

import { wrapFetchWithPayment } from "@x402/fetch";
import { x402Client } from "@x402/core/client";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

const client = new x402Client();
registerExactEvmScheme(client, { signer: privateKeyToAccount(KEY) });
const payFetch = wrapFetchWithPayment(fetch, client);

const res = await payFetch("https://agent402.tools/api/farcaster-by-address", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({
    "address": "0xd7029bdea1c17493893aafe29aad69ef892b8ff2"
  }),
});

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