# Farcaster Profile Lookup by Ethereum Address

> Farcaster Profile Lookup by Ethereum Address is a paid API for AI agents from agent402.tools, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-15).

Reverse-lookups an Ethereum address to its associated Farcaster account profile via verified address linkage

## Facts

- Endpoint: POST https://agent402.tools/api/farcaster-by-address
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/farcaster-profile-lookup-by-ethereum-address-365ab73c
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_aVB7UKJjYCZLrr_aO2qsA

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability farcaster-profile-lookup-by-ethereum-address-365ab73c -d '<json body>'
```

Example prompt: Can you tell me who this Ethereum address belongs to on Farcaster — 0x742d35Cc6634C0532925a3b8D4C9C6B9a2b4F1e8? I want their username, bio, and follower count.

## When to prefer this

Use this endpoint when you have an Ethereum wallet address and need to identify the corresponding Farcaster social identity — for example, to label on-chain actors with their social profiles, enrich NFT holder lists, or attribute blockchain transactions to social accounts. Prefer this over forward-lookup (username→address) when the address is your starting point.

## Known failure modes

- Address not verified on Farcaster returns found=false rather than an error
- Malformed or non-0x-prefixed address may return a validation error
- Address verified on Farcaster under a deactivated account may return incomplete profile data
- Network timeout if Farcaster hub is temporarily unavailable

## How this service works

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.

## Output

Returns a JSON object with found=true and profile fields (FID, username, display name, bio, follower count, following count, Warpcast URL) if the address has a verified Farcaster account, or found=false if no Farcaster account is linked to that address.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "address": {
   "type": "string",
   "description": "Ethereum address (0x-prefixed 40-hex)."
  }
 }
}
```

## Response schema (JSON Schema)

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

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/farcaster-profile-lookup-by-ethereum-address-365ab73c/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agent402.tools](https://www.zero.xyz/host/agent402.tools/llms.txt)