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POST
/
v1
/
submitMessage
Submit signed message
curl --request POST \
  --url https://snapchain-api.neynar.com/v1/submitMessage \
  --header 'Content-Type: application/octet-stream' \
  --header 'x-api-key: <api-key>' \
  --data '"<string>"'
import requests

url = "https://snapchain-api.neynar.com/v1/submitMessage"

payload = "<string>"
headers = {
    "x-api-key": "<api-key>",
    "Content-Type": "application/octet-stream"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)
const options = {
  method: 'POST',
  headers: {'x-api-key': '<api-key>', 'Content-Type': 'application/octet-stream'},
  body: JSON.stringify('<string>')
};

fetch('https://snapchain-api.neynar.com/v1/submitMessage', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));
<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://snapchain-api.neynar.com/v1/submitMessage",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode('<string>'),
  CURLOPT_HTTPHEADER => [
    "Content-Type: application/octet-stream",
    "x-api-key: <api-key>"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}
package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://snapchain-api.neynar.com/v1/submitMessage"

	payload := strings.NewReader("\"<string>\"")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("x-api-key", "<api-key>")
	req.Header.Add("Content-Type", "application/octet-stream")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}
HttpResponse<String> response = Unirest.post("https://snapchain-api.neynar.com/v1/submitMessage")
  .header("x-api-key", "<api-key>")
  .header("Content-Type", "application/octet-stream")
  .body("\"<string>\"")
  .asString();
require 'uri'
require 'net/http'

url = URI("https://snapchain-api.neynar.com/v1/submitMessage")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["x-api-key"] = '<api-key>'
request["Content-Type"] = 'application/octet-stream'
request.body = "\"<string>\""

response = http.request(request)
puts response.read_body
{
  "data": {
    "fid": 2,
    "timestamp": 48994466,
    "network": "FARCASTER_NETWORK_MAINNET",
    "castAddBody": {
      "embedsDeprecated": [
        "<string>"
      ],
      "mentions": [
        2
      ],
      "text": "<string>",
      "mentionsPositions": [
        123
      ],
      "embeds": [
        {
          "castId": {
            "fid": 2,
            "hash": "0x03aff391a6eb1772b20b4ead9a89f732be75fe27"
          }
        }
      ],
      "parentCastId": {
        "fid": 2,
        "hash": "0x03aff391a6eb1772b20b4ead9a89f732be75fe27"
      },
      "parentUrl": "chain://eip155:1/erc721:0x39d89b649ffa044383333d297e325d42d31329b2"
    },
    "type": "MESSAGE_TYPE_CAST_ADD"
  },
  "hash": "0xd2b1ddc6c88e865a33cb1a565e0058d757042974",
  "hashScheme": "HASH_SCHEME_BLAKE3",
  "signature": "aSDinaTvuI8gbWludGxpZnk=",
  "signatureScheme": "SIGNATURE_SCHEME_ED25519",
  "signer": "<string>"
}
{
  "errCode": "<string>",
  "presentable": true,
  "name": "<string>",
  "code": 123,
  "details": "<string>",
  "metadata": {
    "errcode": [
      "<string>"
    ]
  }
}

Authorizations

ā€‹
x-api-key
string
header
default:NEYNAR_API_DOCS
required

API key to authorize requests

Body

application/octet-stream

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

A successful response.

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.

ā€‹
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.

ā€‹
hash
string
required
Pattern: ^0x[0-9a-fA-F]{40}$
Example:

"0xd2b1ddc6c88e865a33cb1a565e0058d757042974"

ā€‹
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
ā€‹
signature
string<byte>
required
Pattern: ^(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=)?$
ā€‹
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
ā€‹
signer
string
required
Pattern: ^0x[0-9a-fA-F]+$