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Status

Blog

Overview

Farcaster API V2

Onchain

Farcaster Hub API

Neynar SDK

Github

POST

validateMessage

curl --request POST \
  --url https://hub-api.neynar.com/v1/validateMessage \
  --header 'Content-Type: application/octet-stream' \
  --header 'x-api-key: <api-key>'

{
  "valid": true,
  "message": {
    "data": {
      "fid": 2,
      "timestamp": 48994466,
      "network": "FARCASTER_NETWORK_MAINNET",
      "castAddBody": {
        "embedsDeprecated": [
          "<string>"
        ],
        "mentions": [
          2
        ],
        "parentCastId": {
          "fid": 2,
          "hash": "0x03aff391a6eb1772b20b4ead9a89f732be75fe27"
        },
        "parentUrl": "chain://eip155:1/erc721:0x39d89b649ffa044383333d297e325d42d31329b2",
        "text": "<string>",
        "mentionsPositions": [
          123
        ],
        "embeds": [
          {
            "castId": {
              "fid": 2,
              "hash": "0x03aff391a6eb1772b20b4ead9a89f732be75fe27"
            }
          }
        ]
      }
    },
    "hash": "0xd2b1ddc6c88e865a33cb1a565e0058d757042974",
    "hashScheme": "HASH_SCHEME_BLAKE3",
    "signature": "aSDinaTvuI8gbWludGxpZnk=",
    "signatureScheme": "SIGNATURE_SCHEME_ED25519",
    "signer": "<string>"
  }
}

Authorizations

x-api-key

string

header

default:NEYNAR_API_DOCS

required

API key to authorize requests

Body

application/octet-stream · file

A Message is a delta operation on the Farcaster network. The message protobuf is an envelope that wraps a MessageData object and contains a hash and signature which can verify its authenticity.

The body is of type file.

Response

200

application/json

A successful response.

valid

boolean

required

message

object

required

A Message is a delta operation on the Farcaster network that represents a state change. Messages are the fundamental unit of data in Farcaster and can represent various actions like:

Creating or removing casts (posts)
Adding or removing reactions
Following or unfollowing users
Updating profile data
Verifying Ethereum addresses

Each message contains:

A MessageData object with the actual content
A hash of the content for integrity verification
A cryptographic signature to prove authenticity
The signer's public key for verification

Messages are immutable once created and form an append-only log of all user actions on the network.

message.data

object

required

Represents a new cast (post) being created in the Farcaster network. A cast can include text content, mentions of other users, embedded URLs, and references to parent posts for replies.

message.data.fid

integer

required

The unique identifier (FID) of the user who created this message. FIDs are assigned sequentially when users register on the network and cannot be changed.

Example:

2

message.data.timestamp

integer

required

Seconds since Farcaster Epoch (2021-01-01T00:00:00Z). Used to order messages chronologically and determine the most recent state. Must be within 10 minutes of the current time when the message is created.

Example:

48994466

message.data.network

enum<string>

default:FARCASTER_NETWORK_MAINNET

required

Farcaster network the message is intended for.

FARCASTER_NETWORK_MAINNET: Public primary network
FARCASTER_NETWORK_TESTNET: Public test network
FARCASTER_NETWORK_DEVNET: Private test network

Available options:

FARCASTER_NETWORK_MAINNET,

FARCASTER_NETWORK_TESTNET,

FARCASTER_NETWORK_DEVNET

message.data.castAddBody

object

required

The content and metadata of the new cast, including the text, mentions, embeds, and any parent references for replies.

message.hash

string

required

Example:

"0xd2b1ddc6c88e865a33cb1a565e0058d757042974"

message.hashScheme

enum<string>

default:HASH_SCHEME_BLAKE3

required

Type of hashing scheme used to produce a digest of MessageData. - HASH_SCHEME_BLAKE3: Default scheme for hashing MessageData

Available options:

HASH_SCHEME_BLAKE3

message.signature

string

required

message.signatureScheme

enum<string>

default:SIGNATURE_SCHEME_ED25519

required

Type of signature scheme used to sign the Message hash

SIGNATURE_SCHEME_ED25519: Ed25519 signature (default)
SIGNATURE_SCHEME_EIP712: ECDSA signature using EIP-712 scheme

Available options:

SIGNATURE_SCHEME_ED25519,

SIGNATURE_SCHEME_EIP712

message.signer

string

required

Submit signed message Page of events

curl --request POST \
  --url https://hub-api.neynar.com/v1/validateMessage \
  --header 'Content-Type: application/octet-stream' \
  --header 'x-api-key: <api-key>'

{
  "valid": true,
  "message": {
    "data": {
      "fid": 2,
      "timestamp": 48994466,
      "network": "FARCASTER_NETWORK_MAINNET",
      "castAddBody": {
        "embedsDeprecated": [
          "<string>"
        ],
        "mentions": [
          2
        ],
        "parentCastId": {
          "fid": 2,
          "hash": "0x03aff391a6eb1772b20b4ead9a89f732be75fe27"
        },
        "parentUrl": "chain://eip155:1/erc721:0x39d89b649ffa044383333d297e325d42d31329b2",
        "text": "<string>",
        "mentionsPositions": [
          123
        ],
        "embeds": [
          {
            "castId": {
              "fid": 2,
              "hash": "0x03aff391a6eb1772b20b4ead9a89f732be75fe27"
            }
          }
        ]
      }
    },
    "hash": "0xd2b1ddc6c88e865a33cb1a565e0058d757042974",
    "hashScheme": "HASH_SCHEME_BLAKE3",
    "signature": "aSDinaTvuI8gbWludGxpZnk=",
    "signatureScheme": "SIGNATURE_SCHEME_ED25519",
    "signer": "<string>"
  }
}