Send a Transaction

This guide covers the complete transaction flow for Flex vaults — from creating a transfer to confirmation on-chain.

Note

This guide focuses on Flex vault transactions. Standard vault transactions require all signers to participate in a real-time MPC ceremony via the Tholos app.

1. Estimate fees

Before creating a transaction, estimate the network fee:

cURL

curl -X POST https://api.tholos.app/transaction/estimate-fee \
  -H "Authorization: Bearer $THOLOS_API_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "vaultId": 123,
    "chain": "ethereum",
    "to": "0xRecipient...",
    "amount": "1000000000000000000"
  }'

JavaScript

const response = await fetch("https://api.tholos.app/transaction/estimate-fee", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.THOLOS_API_TOKEN}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    vaultId: 123,
    chain: "ethereum",
    to: "0xRecipient...",
    amount: "1000000000000000000",
  }),
});
const data = await response.json();
console.log("Estimated fee:", data);

2. Create the transaction

cURL

curl -X POST https://api.tholos.app/transaction/transfer \
  -H "Authorization: Bearer $THOLOS_API_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "vaultId": 123,
    "chain": "ethereum",
    "to": "0xRecipient...",
    "amount": "1000000000000000000",
    "tokenAddress": null,
    "note": "Monthly treasury distribution"
  }'

JavaScript

const response = await fetch("https://api.tholos.app/transaction/transfer", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.THOLOS_API_TOKEN}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    vaultId: 123,
    chain: "ethereum",
    to: "0xRecipient...",
    amount: "1000000000000000000",
    tokenAddress: null,
    note: "Monthly treasury distribution",
  }),
});
const data = await response.json();
console.log("Transaction ID:", data.id);

The response includes the new transaction with state DRAFT or SUBMITTED depending on your vault configuration.

3. Approve the transaction

Vault signers need to approve the transaction. The approval flow uses an MPC challenge-response.

Get a challenge — the signer requests a challenge for the transaction:

curl https://api.tholos.app/transaction/{txId}/challenge \
-H "Authorization: Bearer $SIGNER_TOKEN"

Approve — the signer submits their approval:

curl -X POST https://api.tholos.app/transaction/{txId}/approve \
  -H "Authorization: Bearer $SIGNER_TOKEN"

Repeat until the vault’s approval threshold is met.

4. Transaction completes

Once the threshold number of approvals is reached:

1. The server automatically signs the transaction using MPC
2. The signed transaction is broadcast to the blockchain
3. The state updates to SUCCEEDED when confirmed on-chain

5. Check transaction status

cURL

curl https://api.tholos.app/transaction/{txId} \
  -H "Authorization: Bearer $THOLOS_API_TOKEN"

JavaScript

const response = await fetch("https://api.tholos.app/transaction/456", {
  headers: {
    Authorization: `Bearer ${process.env.THOLOS_API_TOKEN}`,
  },
});
const data = await response.json();
console.log("State:", data.state);
console.log("Hash:", data.txHash);

Other transaction types

Sign a message

curl -X POST https://api.tholos.app/transaction/message \
-H "Authorization: Bearer $THOLOS_API_TOKEN" \
-H "Content-Type: application/json" \
-d '{
  "vaultId": 123,
  "chain": "ethereum",
  "message": "Hello from Tholos"
}'

Smart contract interaction

curl -X POST https://api.tholos.app/transaction/contract-interaction \
  -H "Authorization: Bearer $THOLOS_API_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "vaultId": 123,
    "chain": "ethereum",
    "to": "0xContractAddress...",
    "data": "0xCalldata...",
    "value": "0"
  }'

ERC-20 token approval

curl -X POST https://api.tholos.app/transaction/erc20-approve \
  -H "Authorization: Bearer $THOLOS_API_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "vaultId": 123,
    "chain": "ethereum",
    "tokenAddress": "0xTokenAddress...",
    "spender": "0xSpenderAddress...",
    "amount": "1000000000000000000"
  }'

Rejecting a transaction

Any signer can reject a pending transaction:

curl -X POST https://api.tholos.app/transaction/{txId}/reject \
  -H "Authorization: Bearer $SIGNER_TOKEN"

Next steps

• Transaction concepts — understand the full state machine
• Manage Policies — set up spending limits and whitelists
• API Reference — see all transaction endpoints