Solana Sign & Broadcast Transaction APIs

Firekeeper

Sign a Solana transaction without broadcasting it. Perfect for workflows where you need to inspect, store, or conditionally broadcast transactions.

Features:

• Sign serialized transactions or assemble from instructions
• Configure priority fees and compute limits
• Returns both signature and signed transaction payload

Example - Sign from instructions:

curl -X POST https://api.thirdweb.com/v1/solana/sign-transaction \
  -H "Content-Type: application/json" \
  -H "x-secret-key: YOUR_SECRET_KEY" \
  -d '{
    "from": "8JBLmveV4YF5AQ7EVnKJgyj6etGgVkPp3tYqQMTu3p5B",
    "chainId": "solana:devnet",
    "instructions": [
      {
        "programId": "11111111111111111111111111111111",
        "accounts": [
          {
            "address": "8JBLmveV4YF5AQ7EVnKJgyj6etGgVkPp3tYqQMTu3p5B",
            "isSigner": true,
            "isWritable": true
          },
          {
            "address": "FhtwVYF1wKAm7fWmE2N5P2eCv13wt2aT8W4Q9NQ9YcJH",
            "isSigner": false,
            "isWritable": true
          }
        ],
        "data": "02000000e803000000000000",
        "encoding": "hex"
      }
    ],
    "priorityFee": {
      "type": "manual",
      "microLamportsPerUnit": 1000
    }
  }'

Response:

{
  "result": {
    "signature": "3TZx4Ev7fWN7jk7CHTrxmsf9cXB1LQjs44aYGuC9kPYcyJ8D1V8efFgAfL9QGmxZXZMpDnwhzUbBeAf7dByoDwyx",
    "signedTransaction": "AQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAgIAAQIDBAUGBwgJ..."
  }
}

Broadcast a previously signed transaction and wait for confirmation. The endpoint polls the network until the transaction is confirmed or times out after 30 seconds.

Features:

• Broadcasts signed transactions to Solana
• Waits for confirmation before returning
• Detailed error messages for failed transactions
• Returns signature (Solana's equivalent of transaction hash)

Example:

curl -X POST https://api.thirdweb.com/v1/solana/broadcast-transaction \
  -H "Content-Type: application/json" \
  -H "x-secret-key: YOUR_SECRET_KEY" \
  -d '{
    "chainId": "solana:devnet",
    "signedTransaction": "AQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAgIAAQIDBAUGBwgJ..."
  }'

Success Response:

{
  "result": {
    "signature": "5ttCNobho7nk5F1Hh4pU4d9T2o1yAFn3p1w8z8jk2jKd9KWCKN6dzyuT5xP1ny4wz9f5xCLjAF6Y9s9EoTW4aE1X"
  }
}

Error Response (Transaction Failed):

{
  "message": "Transaction failed at instruction 0",
  "error": {
    "transactionError": {
      "InstructionError": [0, "InsufficientFunds"]
    },
    "instructionIndex": 0,
    "instructionError": "InsufficientFunds",
    "signature": "5ttCNobho7nk5F1Hh4pU4d9T2o1yAFn3p1w8z8jk2jKd9KWCKN6dzyuT5xP1ny4wz9f5xCLjAF6Y9s9EoTW4aE1X"
  }
}

Sign a transaction, then broadcast it:

# Step 1: Sign the transaction
SIGNED_TX=$(curl -X POST https://api.thirdweb.com/v1/solana/sign-transaction \
  -H "Content-Type: application/json" \
  -H "x-secret-key: YOUR_SECRET_KEY" \
  -d '{
    "from": "8JBLmveV4YF5AQ7EVnKJgyj6etGgVkPp3tYqQMTu3p5B",
    "chainId": "solana:devnet",
    "instructions": [...]
  }' | jq -r '.result.signedTransaction')
 
# Step 2: Broadcast the signed transaction
curl -X POST https://api.thirdweb.com/v1/solana/broadcast-transaction \
  -H "Content-Type: application/json" \
  -H "x-secret-key: YOUR_SECRET_KEY" \
  -d "{
    \"chainId\": \"solana:devnet\",
    \"signedTransaction\": \"$SIGNED_TX\"
  }"

The broadcast endpoint provides detailed error information:

• 400: Transaction failed (simulation or on-chain) - includes error details, instruction index, and signature
• 504: Transaction timeout - not confirmed within 30 seconds
• 500: Server error during broadcast

All errors include the transaction signature when available, allowing you to look up the transaction on Solana explorers for debugging.

• Signature = Transaction Hash: In Solana, the "signature" is equivalent to an EVM transaction hash - use it to look up transactions on explorers
• Confirmation: The broadcast endpoint waits for "confirmed" status before returning (typically 1-2 seconds on Solana)
• Timeout: 30-second maximum wait time for confirmation
• Preflight Checks: Failed transactions are caught during simulation before being sent to the network when possible