Proxy API

Submitting to Proxy

proxy_submitTransaction	Submits a signed transaction to the proxy.
proxy_faucetDrip	Distribute funds from the proxy's account to the specified account.
proxy_evmSignCertificate	Cross-sign a transaction certificate using secp256k1 for EVM verification.

proxy_submitTransaction

Submit a transaction to the proxy to be forwarded to and settled on the network. Upon receipt of the transaction, if the transaction is complete, the proxy will perform the following steps:

• Submit the signed transaction to all validators known to the proxy.

• Accumulate signatures from all validators which attest that the transaction is valid.

• Submit a transaction certificate (composed of the transaction and a quorum of validator signatures) to all validators known to the proxy.

If the transaction is incomplete, the proxy will store the transaction and await additional requests which provide the missing information.

The sender's transaction signature is computed using Ed25519 where:

• the public key is stored in Transaction.sender .

• the message to be signed is the Transaction struct serialized using the BCS format with the following special rule:

  • Numerical string Amount/Balance fields are encoded as a litte-endian unsigned 256-bit number as an array of uint8 of length 32.

BCS serialization libraries are available for several languages:

• Rust: the zefchain BCS library as a serde backend

• Typescript/Javascript: the Mysten Labs BCS library

Parameters
transaction	Transaction: A transaction of any ClaimType.
signature	SignatureOrMultiSig: A (multi)signature over the transaction created by Transaction.sender and having the verifier signatures field set to the empty list prior to signing in the case of ExternalClaims.

Returns
ProxySubmitTransactionResult	Success: with a transaction certificate if the transaction is complete and was successfully submitted and validated. IncompleteMultiSigs: A flag indicating that the transaction is incomplete and has been stored on the proxy for eventual completion and submission.

POST / proxy_submitTransaction

Curl:

curl -X POST 'https://testnet.api.fast.xyz/proxy' \
     --header 'Content-Type: application/json' \
     --data '{
       "jsonrpc": "2.0",
       "id": 1,
       "method": "proxy_submitTransaction",
       "params": {
         "transaction": {
           "sender": [54,128,54,206,88,243,124,101,147,238,105,180,78,172,190,12,193,195,118,236,177,124,79,251,192,63,114,196,255,73,74,81],
           "recipient": [75,164,223,195,221,101,117,31,251,60,194,50,41,1,83,17,79,28,61,165,140,36,12,127,122,60,161,218,118,145,112,210],
           "nonce": 0,
           "timestamp_nanos": 1769705752161000000,
           "claim": {
             "TokenTransfer": {
               "token_id": [250,87,94,112,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],
               "amount": "ffff",
               "user_data": null
             }
           },
           "archival": true
         },
         "signature": {
           "Signature": [228,162,180,83,46,167,133,230,176,100,60,110,57,65,23,113,101,204,242,193,125,59,88,232,122,6,90,118,41,159,94,108,20,181,224,234,57,42,35,95,4,186,62,128,68,213,212,46,214,155,241,163,147,120,155,69,201,1,29,63,106,22,75,15]
         }
       }
     }'

Server response:

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": 
    {
      "Success": 
        {
          "envelope":
            {
              "transaction":
                {
                  "sender": [54,128,54,206,88,243,124,101,147,238,105,180,78,172,190,12,193,195,118,236,177,124,79,251,192,63,114,196,255,73,74,81],
                  "recipient": [75,164,223,195,221,101,117,31,251,60,194,50,41,1,83,17,79,28,61,165,140,36,12,127,122,60,161,218,118,145,112,210],
                  "nonce": 0,
                  "timestamp_nanos": 1769705752161000000,
                  "claim": 
                    {
                      "TokenTransfer":
                        {
                          "token_id": [250,87,94,112,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],
                          "amount": "ffff",
                          "user_data": null
                        }
                    },
                  "archival": true
              },
            "signature":
              {
                "Signature": [228,162,180,83,46,167,133,230,176,100,60,110,57,65,23,113,101,204,242,193,125,59,88,232,122,6,90,118,41,159,94,108,20,181,224,234,57,42,35,95,4,186,62,128,68,213,212,46,214,155,241,163,147,120,155,69,201,1,29,63,106,22,75,15]
              }
          },
          "signatures": 
            [
              [
                [223,165,168,37,72,213,141,191,209,124,158,179,40,24,196,122,92,162,184,248,231,218,132,148,44,167,202,12,126,87,249,141],
                [95,227,196,114,53,242,118,17,88,202,2,186,132,39,158,203,199,42,252,162,208,162,93,83,168,79,145,250,225,228,244,45,131,200,28,80,73,80,213,164,50,7,240,158,32,196,163,193,225,15,169,236,149,62,228,13,149,125,53,158,20,74,115,1]
              ],
              [
                [236,249,103,252,146,0,130,223,133,72,40,87,67,21,187,13,100,52,193,194,242,152,67,181,8,2,150,72,51,230,245,169],
                [80,65,124,70,9,222,103,175,74,243,129,191,79,205,119,80,41,194,224,73,214,119,154,64,107,201,247,238,110,98,151,185,156,47,5,75,247,176,90,179,158,127,26,149,215,45,142,235,120,11,235,165,86,205,247,219,34,166,149,186,163,111,94,9]
              ],
              [
                [150,20,92,12,163,133,206,208,191,189,42,178,133,120,224,172,183,116,145,47,243,232,221,22,110,243,38,177,23,139,10,120],
                [26,229,199,218,49,147,173,149,87,246,144,213,22,73,18,80,3,122,177,18,83,197,212,112,188,76,155,161,2,206,135,224,43,13,117,143,53,255,153,249,50,12,85,129,13,14,128,73,159,238,21,14,19,61,122,202,203,5,247,35,134,61,38,9]
              ]
            ]
        }
    }
}

---

proxy_faucetDrip

Distribute funds from the proxy's account to the specified account.

Parameters
recipient	FastSetAddress: Account that should receive the funds.
amount	Amount: Amount of funds that should be added.
token_id	Option<TokenId>: If None, funds will be in the default token. If a TokenId is passed, funds will be in that token.

POST / proxy_faucetDrip

Curl:

curl -X POST 'https://testnet.api.fast.xyz/proxy' \
     --header 'Content-Type: application/json' \
     --data '{
       "jsonrpc": "2.0",
       "id": 1,
       "method": "proxy_faucetDrip",
       "params": {
         "recipient": [54,128,54,206,88,243,124,101,147,238,105,180,78,172,190,12,193,195,118,236,177,124,79,251,192,63,114,196,255,73,74,81],
         "amount": "3635c9adc5dea00000",
         "token_id": null
       }
     }'

Note: 3635c9adc5dea00000 = 1000 × 10¹⁸ = 1000 SET in raw units.

Server response:

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": null
}

---

proxy_evmSignCertificate

Cross-sign a transaction certificate using secp256k1 for EVM verification. Produces a signature that can be verified by EVM smart contracts, used for bridging and cross-chain verification.

Parameters
certificate	TransactionCertificate: The certificate to cross-sign.

Returns
EVM signature	An EVM-compatible signature object that can be verified by EVM smart contracts, used for bridging and cross-chain verification.

POST / proxy_evmSignCertificate

Curl:

curl -X POST 'https://testnet.api.fast.xyz/proxy' \
     --header 'Content-Type: application/json' \
     --data '{
       "jsonrpc": "2.0",
       "id": 1,
       "method": "proxy_evmSignCertificate",
       "params": {
         "certificate": {
           "envelope": {
             "transaction": { "..." : "..." },
             "signature": { "Signature": ["..."] }
           },
           "signatures": [["...", "..."]]
         }
       }
     }'

---

Querying the Validator

proxy_getAccountInfo	Returns information regarding a specific account from a validator known to the proxy.
proxy_getTokenInfo	Returns information regarding a set of tokens from some validator known to the proxy.

proxy_getAccountInfo

Return information regarding a specific account from some validator known to the proxy.

Parameters
address	FastSetAddress: The designated account to query.
token_balances_filter	Option<Vec<TokenId>>: The set of token types for which a balance request will be made. If this parameter is omitted, no custom token balances will be returned. If it is present and empty, the balance of all tokens owned by this account will be queried.
state_key_filter	Option<Vec<StateKey>>: The set of state fields created by this account to be returned. If this parameter is omitted, no state fields will be returned; if it is present and empty, all state fields created by this account will be returned.
certificate_by_nonce	Option<NonceRange>: If passed, a list of transaction certificates within the nonce range specified by this parameter submitted by account address will be returned (omitting those which do not exist or have been pruned from the validator database).

Returns
AccountInfoResponse	AccountInfoResponse for the requested account.

POST / proxy_getAccountInfo

Curl:

curl -X POST 'https://testnet.api.fast.xyz/proxy' \
     --header 'Content-Type: application/json' \
     --data '{
       "jsonrpc": "2.0",
       "id": 1,
       "method": "proxy_getAccountInfo",
       "params": {
         "address": [54,128,54,206,88,243,124,101,147,238,105,180,78,172,190,12,193,195,118,236,177,124,79,251,192,63,114,196,255,73,74,81],
         "token_balances_filter": null,
         "state_key_filter": null,
         "certificate_by_nonce": null
       }
     }'

Server response:

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": 
    {
      "sender": [54,128,54,206,88,243,124,101,147,238,105,180,78,172,190,12,193,195,118,236,177,124,79,251,192,63,114,196,255,73,74,81],
      "balance": "0",
      "next_nonce": 0,
      "pending_confirmation": null,
      "requested_state": [],
      "requested_certificates": null,
      "requested_validated_transaction": null,
      "token_balance": []
    }
}

---

proxy_getTokenInfo

Return information regarding a set of tokens from some validator known to the proxy.

Parameters
token_ids	Vec<TokenId>: An array of TokenIds to look up.

Returns
TokenInfoResponse	Contains data for all requested tokens.

POST / proxy_getTokenInfo

Curl:

curl -X POST 'https://testnet.api.fast.xyz/proxy' \
     --header 'Content-Type: application/json' \
     --data '{
       "jsonrpc": "2.0",
       "id": 1,
       "method": "proxy_getTokenInfo",
       "params": {
         "token_ids": [
           [250,87,94,112,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
         ]
       }
     }'

Server response:

{
  "jsonrpc": "2.0",
  "id": 1,
  "result":
    {
      "requested_token_metadata":
        [
          [
            [250,87,94,112,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],
            null
          ]
        ]
    }
}

---

Error Codes

The proxy uses standard JSON-RPC 2.0 error codes, plus custom codes for application-specific errors.

Code	Message	Description
-32700	Parse error	Malformed JSON in request body
-32601	Method not found	The requested method does not exist
-32602	Invalid params	Missing or invalid parameters
-32000	Server error	Transaction validation failure (e.g., nonce mismatch, insufficient balance)
-32003	Throttled	Rate limit exceeded (e.g., faucet cooldown)

Error response format:

{
  "jsonrpc": "2.0",
  "id": 1,
  "error": {
    "code": -32000,
    "message": "expected nonce is 1 but tx has 0"
  }
}

Some errors include an additional data field with details:

{
  "jsonrpc": "2.0",
  "id": 1,
  "error": {
    "code": -32602,
    "message": "Invalid params",
    "data": "missing field `certificate` at line 1 column 2"
  }
}