jiayaoqijia Farcaster
Interact with Farcaster — the decentralized social protocol — via the Neynar v2 REST API.
Setup
export NEYNAR_API_KEY="your-api-key" # required for all ops
export NEYNAR_SIGNER_UUID="your-signer-uuid" # required for write ops
Get API key at https://neynar.com
API
Base: https://api.neynar.com/v2/farcaster
Read Operations (Free tier)
User's casts by FID:
web_fetch url="https://api.neynar.com/v2/farcaster/feed/user/3?limit=10" headers="api_key: NEYNAR_API_KEY"
User lookup by username:
web_fetch url="https://api.neynar.com/v2/farcaster/user/by_username?username=vitalik" headers="api_key: NEYNAR_API_KEY"
User lookup by FID:
web_fetch url="https://api.neynar.com/v2/farcaster/user/bulk?fids=3" headers="api_key: NEYNAR_API_KEY"
Cast thread/replies:
web_fetch url="https://api.neynar.com/v2/farcaster/cast/conversation?identifier=0xHASH&type=hash" headers="api_key: NEYNAR_API_KEY"
Write Operations (Require signer)
Post a cast:
exec command="curl -s -X POST 'https://api.neynar.com/v2/farcaster/cast' -H 'api_key: NEYNAR_API_KEY' -H 'Content-Type: application/json' -d '{\"signer_uuid\":\"SIGNER_UUID\",\"text\":\"Hello Farcaster!\"}'"
Post to a channel:
exec command="curl -s -X POST 'https://api.neynar.com/v2/farcaster/cast' -H 'api_key: NEYNAR_API_KEY' -H 'Content-Type: application/json' -d '{\"signer_uuid\":\"SIGNER_UUID\",\"text\":\"gm\",\"channel_id\":\"base\"}'"
Reply to a cast:
exec command="curl -s -X POST 'https://api.neynar.com/v2/farcaster/cast' -H 'api_key: NEYNAR_API_KEY' -H 'Content-Type: application/json' -d '{\"signer_uuid\":\"SIGNER_UUID\",\"text\":\"Great point!\",\"parent\":\"0xHASH\"}'"
Like a cast:
exec command="curl -s -X POST 'https://api.neynar.com/v2/farcaster/reaction' -H 'api_key: NEYNAR_API_KEY' -H 'Content-Type: application/json' -d '{\"signer_uuid\":\"SIGNER_UUID\",\"reaction_type\":\"like\",\"target\":\"0xHASH\"}'"
Search (Paid tier)
Search casts by keyword:
web_fetch url="https://api.neynar.com/v2/farcaster/cast/search?q=ethereum&limit=10" headers="api_key: NEYNAR_API_KEY"
Search channels:
web_fetch url="https://api.neynar.com/v2/farcaster/channel/search?q=defi" headers="api_key: NEYNAR_API_KEY"
Free vs Paid
| Feature | Free |
|---|---|
| Post cast | Yes |
| User lookup | Yes |
| User feed | Yes |
| Like/recast | Yes |
| Following feed | Yes |
| Cast search | Paid |
| Channel feed | Paid |
| Channel search | Paid |
Rate limit: 300 req/min (free tier)
Use Cases
- Agent social presence: post updates, market alerts, DeFi insights to Farcaster
- Community monitoring: track mentions, replies, and channel activity
- Social signals: correlate social engagement with token performance
- Agent-to-agent: coordinate with other agents via Farcaster channels