Decoding Transaction Data - Helius LaserStream

When you receive transaction data from Laserstream, there are two important things to look for:

Message → What the user wanted to do (their signed proposal)
Meta → What actually happened (the execution result)

The challenge: Raw transaction data comes as binary byte arrays like <Buffer 00 bf a0 e8...> instead of readable addresses and signatures. This guide shows you how to: Decode that binary data into human-readable format, extract meaningful information, and understand the complete transaction story from proposal to execution.

A live stream, no decoding

Run the minimal client below. The filter flags drop vote and failed transactions, and the accountInclude array limits results to activity that touches the Jupiter program ID.

import { subscribe, CommitmentLevel, SubscribeUpdate, LaserstreamConfig } from 'helius-laserstream';

async function runTransactionSubscription() {
  const config: LaserstreamConfig = {
    apiKey: 'YOUR_API_KEY', // from https://dashboard.helius.dev/
    endpoint: 'https://laserstream-mainnet-ewr.helius-rpc.com', // pick the closest region
  };

  const request = {
    transactions: {
      "Jupiter-transactions": {
        vote: false,
        failed: false,
        accountInclude: ['JUP6LkbZbjS1jKKwapdHNy74zcZ3tLUZoi5QNyVTaV4']
      }
    },
    commitment: CommitmentLevel.PROCESSED,
    accounts: {}, slots: {}, transactionsStatus: {}, blocks: {}, blocksMeta: {}, entry: {}, accountsDataSlice: []
  };

  const stream = await subscribe(
    config,
    request,
    (u: SubscribeUpdate) => console.log('💸 Transaction update', u),
    console.error
  );

  console.log(`✅ stream id → ${stream.id}`);
  process.on('SIGINT', () => { stream.cancel(); process.exit(0); });
}
runTransactionSubscription().catch(console.error);

Your console now shows a wrapper—filters, createdAt plus a transaction branch that hides two children:

transaction.transaction.transaction → the signed message
transaction.transaction.meta → the execution meta

{
 filters: [ 'Jupiter-transactions' ],
  account: undefined,
  transaction: {
    transaction: {
      signature: <Buffer 00 bf a0 e8 9f cc 84 0c a4 83 e3 97 cd b7 57 e2 2b bc 1d ca 8c a6 1b ce b5 57 d7 47 5e ec 1f 46 ae b2 2d 6a 12 cb 88 48 1d 07 bf f6 b2 d3 a8 0b c9 04 ... 14 more bytes>,
      transaction: [Object],
      meta: [Object],
      index: '1177'
    },
    slot: '351704819'
  },
  transactionStatus: undefined,
  block: undefined,
  blockMeta: undefined,
  entry: undefined,
  ping: undefined,
  pong: undefined,
  createdAt: 2025-07-07T10:58:44.403Z
}

Everything that looks like Uint8Array remains opaque for the moment. When you run the script with the decoding function, you’ll see the actual nested structure with readable addresses:

{
  "filters": ["Jupiter-transactions"],
  "account": undefined,
  "transaction": {
    "transaction": {
      "signature": "5u62i53R1Hdc4thm6DQTNWNkyypuJJSaXSMwwQDxNqKMaAw62H1Xa3Md7QDhYjoPk5dCPg18fwz83kUR6TrMviTx",
      "transaction": {
        "message": {
          "header": {
            "numRequiredSignatures": 1,
            "numReadonlySignedAccounts": 0,
            "numReadonlyUnsignedAccounts": 8
          },
          "accountKeys": [
            "AF9KFSWQeKVxd3kVvFvysWXmATHyYzrN8zN8GtXn4qTF",
            "G9VzXwhDPQ8KRbQAJN6TyGf2gWukYDAvmnXJhPZFev4f",
            "ES9qPxWQVMRZkobJ9yr3U6XSrXzGNLJdSe6p6fS7b82T",
            "JUP6LkbZbjS1jKKwapdHNy74zcZ3tLUZoi5QNyVTaV4",
            "ComputeBudget111111111111111111111111111111",
            "ATokenGPvbdGVxr1b2hvZbsiqW5xWH25efTNsLJA8knL",
            "So11111111111111111111111111111111111111112",
            "11111111111111111111111111111111",
            "TokenkegQfeZyiNwAJbNbGKPFXCWuBvf9Ss623VQ5DA"
          ],
          "recentBlockhash": "8sGjRxJHLJVWqpHt5UdN8qxtLLdgcnLKBpFj9Qrn5PNF",
          "instructions": [
            {
              "programIdIndex": 4,
              "accounts": [],
              "data": "3bjaAzoXPjbY"
            },
            {
              "programIdIndex": 3,
              "accounts": [0, 1, 2, 5, 6, 7, 8],
              "data": "2L1xoA2KEqBgWfGt3fwFJK8k4FPJRJzYHRgH4R3xC8A7"
            }
          ]
        },
        "signatures": [
          "5u62i53R1Hdc4thm6DQTNWNkyypuJJSaXSMwwQDxNqKMaAw62H1Xa3Md7QDhYjoPk5dCPg18fwz83kUR6TrMviTx"
        ]
      },
      "meta": {
        "err": null,
        "fee": 12500,
        "preBalances": [1075517572, 0, 207594496815, 0, 0, 0, 0, 0, 0],
        "postBalances": [1075502572, 1461600, 207594496815, 2001231920, 2039280, 0, 0, 0, 0],
        "innerInstructions": [
          {
            "index": 1,
            "instructions": [
              {
                "programIdIndex": 5,
                "accounts": [1, 2, 0],
                "data": "3Bxs4h24hBtQy9rw"
              }
            ]
          }
        ],
        "logMessages": [
          "Program ComputeBudget111111111111111111111111111111 invoke [1]",
          "Program ComputeBudget111111111111111111111111111111 success",
          "Program JUP6LkbZbjS1jKKwapdHNy74zcZ3tLUZoi5QNyVTaV4 invoke [1]",
          "Program log: Instruction: Swap",
          "Program ATokenGPvbdGVxr1b2hvZbsiqW5xWH25efTNsLJA8knL invoke [2]",
          "Program log: Create",
          "Program TokenkegQfeZyiNwAJbNbGKPFXCWuBvf9Ss623VQ5DA invoke [3]",
          "Program log: Instruction: GetAccountDataSize",
          "Program TokenkegQfeZyiNwAJbNbGKPFXCWuBvf9Ss623VQ5DA consumed 1569 of 242833 compute units",
          "Program return: TokenkegQfeZyiNwAJbNbGKPFXCWuBvf9Ss623VQ5DA pQAAAAAAAAA=",
          "Program TokenkegQfeZyiNwAJbNbGKPFXCWuBvf9Ss623VQ5DA success",
          "Program JUP6LkbZbjS1jKKwapdHNy74zcZ3tLUZoi5QNyVTaV4 success"
        ],
        "preTokenBalances": [],
        "postTokenBalances": [],
        "computeUnitsConsumed": 182564
      },
      "index": "1177"
    },
    "slot": "351709933"
  },
  "transactionStatus": undefined,
  "block": undefined,
  "blockMeta": undefined,
  "entry": undefined,
  "ping": undefined,
  "pong": undefined,
  "createdAt": "2025-01-14T10:58:44.403Z"
}

Decoding the binary data

Why decode? Raw Laserstream data contains signatures, account keys, and hashes as binary Uint8Array objects that are unreadable. You need to convert these to base58 strings to make sense of the transaction. The solution: Laserstream uses Yellowstone gRPC, which provides built-in decoding utilities. Instead of writing separate decoders for each field type, we use one recursive function that converts all binary data to human-readable format.

import bs58 from 'bs58';
import { subscribe, CommitmentLevel, SubscribeUpdate, LaserstreamConfig } from 'helius-laserstream';

// Recursive function to convert all Buffer/Uint8Array fields to base58
function convertBuffers(obj: any): any {
  if (!obj) return obj;
  if (Buffer.isBuffer(obj) || obj instanceof Uint8Array) {
    return bs58.encode(obj);
  }
  if (Array.isArray(obj)) {
    return obj.map(item => convertBuffers(item));
  }
  if (typeof obj === 'object') {
    return Object.fromEntries(
      Object.entries(obj).map(([key, value]) => [key, convertBuffers(value)])
    );
  }
  return obj;
}

async function runTransactionSubscription() {
  const config: LaserstreamConfig = {
    apiKey: 'YOUR_API_KEY', // from https://dashboard.helius.dev/
    endpoint: 'https://laserstream-mainnet-ewr.helius-rpc.com', // pick the closest region
  };

  const request = {
    transactions: {
      "Jupiter-transactions": {
        vote: false,
        failed: false,
        accountInclude: ['JUP6LkbZbjS1jKKwapdHNy74zcZ3tLUZoi5QNyVTaV4']
      }
    },
    commitment: CommitmentLevel.PROCESSED,
    accounts: {}, slots: {}, transactionsStatus: {}, blocks: {}, blocksMeta: {}, entry: {}, accountsDataSlice: []
  };

  const stream = await subscribe(
    config,
    request,
    (update: SubscribeUpdate) => {
      if (update.transaction) {
        // Convert all binary fields to human-readable format
        const decodedTransaction = convertBuffers(update.transaction);
        console.log('💸 Decoded transaction:', JSON.stringify(decodedTransaction, null, 2));
        
        // Or process specific fields
        processTransaction(update.transaction);
      }
    },
    console.error
  );

  console.log(`✅ stream id → ${stream.id}`);
  process.on('SIGINT', () => { stream.cancel(); process.exit(0); });
}

function processTransaction(txUpdate: any) {
  const tx = txUpdate.transaction;
  const meta = tx.meta;
  
  console.log('Transaction Details:');
  console.log('- Signature:', bs58.encode(tx.signature));
  console.log('- Slot:', txUpdate.slot);
  console.log('- Success:', meta.err === null);
  console.log('- Fee:', meta.fee, 'lamports');
  console.log('- Compute Units:', meta.computeUnitsConsumed);
  
  // Account keys are already available in the message
  const message = tx.transaction.message;
  if (message.accountKeys) {
    console.log('- Account Keys:');
    message.accountKeys.forEach((key: Uint8Array, index: number) => {
      console.log(`  ${index}: ${bs58.encode(key)}`);
    });
  }
  
  // Log messages are already UTF-8 strings
  if (meta.logMessages && meta.logMessages.length > 0) {
    console.log('- Log Messages:');
    meta.logMessages.forEach((log: string) => {
      console.log(`  ${log}`);
    });
  }
}

runTransactionSubscription();

This approach leverages the built-in decoding while handling the binary fields that need manual conversion. The transaction structure is already parsed - you just need to convert the binary fields to human-readable format.

Understanding the transaction structure

Now that we can see the decoded data, let’s explore the two main parts of every Laserstream transaction update. Remember from our initial example that each transaction contains two key objects:

Message (Proposal) → transaction.transaction.transaction → the signed message (user’s proposal)
Meta (Execution) → transaction.transaction.meta → the execution metadata (validator’s response)

This two-part structure tells a complete story: what the user requested versus what actually happened. Let’s examine each part in detail.

The proposal: everything inside message

The user creates a message that specifies what, who and until when. Here’s how to decode each part:

Transaction Header

{
  "header": {
    "numRequiredSignatures": 1,
    "numReadonlySignedAccounts": 0,
    "numReadonlyUnsignedAccounts": 5
  }
}

numRequiredSignatures tells the validator how many signatures to verify, while the two numReadonly* values label accounts the runtime can treat as read-only, enabling parallel execution.

Account Keys Dictionary

{
  "accountKeys": [
    "7YttLkHDoNj9wyDur5pM1ejNaAvT9X4eqaYcHQqtj2G5",
    "JUP6LkbZbjS1jKKwapdHNy74zcZ3tLUZoi5QNyVTaV4",
    "TokenkegQfeZyiNwAJbNbGKPFXCWuBvf9Ss623VQ5DA",
    "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
    "So11111111111111111111111111111111111111112",
    "11111111111111111111111111111111"
  ]
}

accountKeys is a plain list of public keys that acts as a lookup table. Every later integer in the transaction - programIdIndex, each element in an instruction’s accounts array - points back into this list by index, saving more than a kilobyte per message.

Protection Against Replay

{
  "recentBlockhash": "8sGjRxJHLJVWqpHt5UdN8qxtLLdgcnLKBpFj9Qrn5PNF"
}

recentBlockhash expires once it scrolls out of the last 150 block-hashes, roughly ninety seconds on mainnet.

Instructions: The Actual Commands

{
  "instructions": [
    {
      "programIdIndex": 10,
      "data": "HnkkG7"
    },
    {
      "programIdIndex": 15,
      "accounts": "3vtmrQMafzDoG2CBz1iqgXPTnC",
      "data": "5jRcjdixRUDKQKUEt6oHJ747HCB3vWb5y"
    }
  ]
}

Each instruction contains three key parts:

Program ID (programIdIndex): Points to an address in the accountKeys array (e.g., index 10 = ComputeBudget111111111111111111111111111111)
Accounts (accounts): A base58-encoded string representing which account indexes this instruction touches
Data (data): The actual instruction data encoded as base58

Due to the convertBuffers function, accounts appears as base58 but actually contains account indices (e.g., "3vtmrQMafzDoG2CBz1iqgXPTnC" decodes to indices [21, 19, 12, 17, 2, 6, 1, 22]) This design means instead of repeating full 32-byte addresses, each instruction just references positions in the lookup table.

Signatures: Proof of Authorization

{
  "signatures": [
    "5u62i53R1Hdc4thm6DQTNWNkyypuJJSaXSMwwQDxNqKMaAw62H1Xa3Md7QDhYjoPk5dCPg18fwz83kUR6TrMviTx"
  ]
}

signatures contains the cryptographic signatures proving the required accounts authorized this transaction. The number of signatures must match header.numRequiredSignatures.

Address Table Lookups

{
  "addressTableLookups": [
    {
      "accountKey": "5Q544fKrFoe6tsEbD7S8EmxGTJYAKtTVhAW5Q5pge4j1",
      "writableIndexes": [0, 1],
      "readonlyIndexes": [2, 3, 4]
    }
  ],
  "versioned": true
}

If versioned is true, addressTableLookups appears with an on-chain table and two index lists. Lookup tables lift the hard cap on address count to dozens while keeping the packet under the 1,232-byte MTU.

How It All Connects: The Flow

Here’s what happens from first principles:

Build the lookup table: accountKeys lists all addresses this transaction will touch
Set the rules: header specifies how many signatures are required and which accounts are read-only
Create the commands: Each instruction points to:
- A program (via programIdIndex → accountKeys[index])
- The accounts it needs (via accounts → multiple accountKeys[index] positions)
- The instruction data (encoded in data)
Add authorization: signatures proves the required accounts approved this transaction
Set expiration: recentBlockhash ensures this transaction can’t be replayed later

The execution: everything inside meta

While the message shows what the user wanted to do, the meta shows what actually happened when validators executed the transaction.

Basic execution information

Success/Failure

{
  "err": null,
  "fee": 12500
}

err: null = success
err: {...} = failure with error details
fee = lamports charged for this transaction

Balance Changes

{
  "preBalances": [1075517572, 0, 207594496815, 0, 0, 0, 0, 0, 0],
  "postBalances": [1075502572, 1461600, 207594496815, 2001231920, 2039280, 0, 0, 0, 0]
}

Balance arrays correspond to the accountKeys array by index:

Account 0: Lost 15000 lamports (fee payment)
Account 1: Gained 1461600 lamports (new account created)
Account 3: Gained 2001231920 lamports (program account)

Compute Usage

{
  "computeUnitsConsumed": 182564
}

Shows how much compute budget was used (out of the requested amount).

Advanced execution details

Inner Instructions

{
  "innerInstructions": [
    {
      "index": 1,
      "instructions": [
        {
          "programIdIndex": 5,
          "accounts": [1, 2, 0],
          "data": "3Bxs4h24hBtQy9rw"
        }
      ]
    }
  ]
}

Inner instructions are additional instructions that programs called during execution. They’re not part of the original transaction but were triggered by the main instructions. Log Messages

{
  "logMessages": [
    "Program ComputeBudget111111111111111111111111111111 invoke [1]",
    "Program ComputeBudget111111111111111111111111111111 success",
    "Program JUP6LkbZbjS1jKKwapdHNy74zcZ3tLUZoi5QNyVTaV4 invoke [1]",
    "Program log: Instruction: Swap",
    "Program ATokenGPvbdGVxr1b2hvZbsiqW5xWH25efTNsLJA8knL invoke [2]",
    "Program log: Create",
    "Program TokenkegQfeZyiNwAJbNbGKPFXCWuBvf9Ss623VQ5DA invoke [3]",
    "Program log: Instruction: GetAccountDataSize",
    "Program TokenkegQfeZyiNwAJbNbGKPFXCWuBvf9Ss623VQ5DA consumed 1569 of 242833 compute units",
    "Program return: TokenkegQfeZyiNwAJbNbGKPFXCWuBvf9Ss623VQ5DA pQAAAAAAAAA=",
    "Program TokenkegQfeZyiNwAJbNbGKPFXCWuBvf9Ss623VQ5DA success",
    "Program JUP6LkbZbjS1jKKwapdHNy74zcZ3tLUZoi5QNyVTaV4 success"
  ]
}

Log messages provide a chronological trace of program execution, showing which programs were called and any custom log messages they output. Token Balance Changes

{
  "preTokenBalances": [],
  "postTokenBalances": [
    {
      "accountIndex": 1,
      "mint": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
      "owner": "7YttLkHDoNj9wyDur5pM1ejNaAvT9X4eqaYcHQqtj2G5",
      "uiTokenAmount": {
        "amount": "1000000",
        "decimals": 6,
        "uiAmount": 1.0,
        "uiAmountString": "1"
      }
    }
  ]
}

Token balance changes show before/after states for SPL token accounts, including the human-readable amounts with proper decimal handling.

Practical decoding patterns

Here are common patterns for extracting useful information from decoded transactions:

// Transaction Success
function isTransactionSuccessful(meta: any): boolean {
  return meta.err === null;
}

function getTransactionFee(meta: any): number {
  return meta.fee;
}

function getComputeUnitsUsed(meta: any): number {
  return meta.computeUnitsConsumed;
}

// Balance Changes
function getBalanceChanges(meta: any, accountKeys: string[]): Array<{account: string, change: number}> {
  const changes = [];
  
  for (let i = 0; i < meta.preBalances.length; i++) {
    const change = meta.postBalances[i] - meta.preBalances[i];
    if (change !== 0) {
      changes.push({
        account: accountKeys[i],
        change: change
      });
    }
  }
  
  return changes;
}

// Program Calls
function getInvokedPrograms(meta: any, accountKeys: string[]): string[] {
  const programs = new Set<string>();
  
  meta.logMessages.forEach((log: string) => {
    const match = log.match(/Program ([1-9A-HJ-NP-Za-km-z]{32,}) invoke/);
    if (match) {
      programs.add(match[1]);
    }
  });
  
  return Array.from(programs);
}

// Token Transfers
function getTokenTransfers(meta: any): Array<{mint: string, from: string, to: string, amount: number}> {
  const transfers = [];
  
  // Compare pre and post token balances
  const preBalances = new Map();
  const postBalances = new Map();
  
  meta.preTokenBalances.forEach((balance: any) => {
    preBalances.set(balance.accountIndex, balance);
  });
  
  meta.postTokenBalances.forEach((balance: any) => {
    postBalances.set(balance.accountIndex, balance);
  });
  
  // Find changes
  for (const [accountIndex, postBalance] of postBalances) {
    const preBalance = preBalances.get(accountIndex);
    const preAmount = preBalance ? parseInt(preBalance.uiTokenAmount.amount) : 0;
    const postAmount = parseInt(postBalance.uiTokenAmount.amount);
    
    if (preAmount !== postAmount) {
      transfers.push({
        mint: postBalance.mint,
        account: postBalance.owner,
        change: postAmount - preAmount,
        decimals: postBalance.uiTokenAmount.decimals
      });
    }
  }
  
  return transfers;
}

Complete example: Jupiter swap decoder

Here’s a complete example that decodes Jupiter swap transactions and extracts meaningful information:

import bs58 from 'bs58';
import { subscribe, CommitmentLevel, SubscribeUpdate, LaserstreamConfig } from 'helius-laserstream';

interface SwapInfo {
  signature: string;
  slot: number;
  user: string;
  inputMint: string;
  outputMint: string;
  inputAmount: number;
  outputAmount: number;
  fee: number;
  success: boolean;
}

function convertBuffers(obj: any): any {
  if (!obj) return obj;
  if (Buffer.isBuffer(obj) || obj instanceof Uint8Array) {
    return bs58.encode(obj);
  }
  if (Array.isArray(obj)) {
    return obj.map(item => convertBuffers(item));
  }
  if (typeof obj === 'object') {
    return Object.fromEntries(
      Object.entries(obj).map(([key, value]) => [key, convertBuffers(value)])
    );
  }
  return obj;
}

function decodeJupiterSwap(txUpdate: any): SwapInfo | null {
  const tx = txUpdate.transaction;
  const meta = tx.meta;
  const message = tx.transaction.message;
  
  // Convert binary fields to readable format
  const signature = bs58.encode(tx.signature);
  const accountKeys = message.accountKeys.map((key: any) => bs58.encode(key));
  
  // Check if this is a Jupiter transaction
  const jupiterProgram = "JUP6LkbZbjS1jKKwapdHNy74zcZ3tLUZoi5QNyVTaV4";
  if (!accountKeys.includes(jupiterProgram)) {
    return null;
  }
  
  // Extract user (first account is typically the fee payer/user)
  const user = accountKeys[0];
  
  // Get token balance changes
  const tokenChanges = getTokenTransfers(meta);
  
  // Find input (negative change) and output (positive change)
  const inputChange = tokenChanges.find(change => change.change < 0);
  const outputChange = tokenChanges.find(change => change.change > 0);
  
  if (!inputChange || !outputChange) {
    return null;
  }
  
  return {
    signature,
    slot: parseInt(txUpdate.slot),
    user,
    inputMint: inputChange.mint,
    outputMint: outputChange.mint,
    inputAmount: Math.abs(inputChange.change),
    outputAmount: outputChange.change,
    fee: meta.fee,
    success: meta.err === null
  };
}

function getTokenTransfers(meta: any): Array<{mint: string, change: number}> {
  const transfers = [];
  
  const preBalances = new Map();
  const postBalances = new Map();
  
  meta.preTokenBalances.forEach((balance: any) => {
    preBalances.set(balance.accountIndex, balance);
  });
  
  meta.postTokenBalances.forEach((balance: any) => {
    postBalances.set(balance.accountIndex, balance);
  });
  
  for (const [accountIndex, postBalance] of postBalances) {
    const preBalance = preBalances.get(accountIndex);
    const preAmount = preBalance ? parseInt(preBalance.uiTokenAmount.amount) : 0;
    const postAmount = parseInt(postBalance.uiTokenAmount.amount);
    
    if (preAmount !== postAmount) {
      transfers.push({
        mint: postBalance.mint,
        change: postAmount - preAmount
      });
    }
  }
  
  return transfers;
}

async function runJupiterSwapMonitor() {
  const config: LaserstreamConfig = {
    apiKey: 'YOUR_API_KEY', // from https://dashboard.helius.dev/
    endpoint: 'https://laserstream-mainnet-ewr.helius-rpc.com', // pick the closest region
  };

  const request = {
    transactions: {
      "Jupiter-swaps": {
        vote: false,
        failed: false,
        accountInclude: ['JUP6LkbZbjS1jKKwapdHNy74zcZ3tLUZoi5QNyVTaV4']
      }
    },
    commitment: CommitmentLevel.PROCESSED,
    accounts: {}, slots: {}, transactionsStatus: {}, blocks: {}, blocksMeta: {}, entry: {}, accountsDataSlice: []
  };

  const stream = await subscribe(
    config,
    request,
    (update: SubscribeUpdate) => {
      if (update.transaction) {
        const swapInfo = decodeJupiterSwap(update.transaction);
        if (swapInfo) {
          console.log('🔄 Jupiter Swap:');
          console.log(`  User: ${swapInfo.user}`);
          console.log(`  Input: ${swapInfo.inputAmount} of ${swapInfo.inputMint}`);
          console.log(`  Output: ${swapInfo.outputAmount} of ${swapInfo.outputMint}`);
          console.log(`  Fee: ${swapInfo.fee} lamports`);
          console.log(`  Success: ${swapInfo.success}`);
          console.log(`  Signature: ${swapInfo.signature}`);
          console.log('---');
        }
      }
    },
    console.error
  );

  console.log(`✅ Jupiter swap monitor started (id: ${stream.id})`);
  process.on('SIGINT', () => { stream.cancel(); process.exit(0); });
}

runJupiterSwapMonitor().catch(console.error);

This example shows how to combine message decoding with meta analysis to extract business-relevant information from complex DeFi transactions.

Key takeaways

Two-part structure: Every transaction has a message (what was requested) and meta (what actually happened)
Binary decoding: Use bs58.encode() to convert binary fields to readable base58 strings
Account key lookups: Instructions reference accounts by index in the accountKeys array
Balance tracking: Compare preBalances and postBalances to see what changed

The key to understanding Solana transactions is recognizing that they’re designed for efficiency: instead of repeating addresses, they use lookup tables and indexes to minimize transaction size while maximizing information density.

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Sending Transactions

Wallet-as-a-Service

Guides

Resources

Decoding and Parsing Transaction Data

A live stream, no decoding

Decoding the binary data

Understanding the transaction structure

The proposal: everything inside message

Transaction Header

Account Keys Dictionary

Protection Against Replay

Instructions: The Actual Commands

Signatures: Proof of Authorization

Address Table Lookups

How It All Connects: The Flow

The execution: everything inside meta

Basic execution information

Advanced execution details

Practical decoding patterns

Complete example: Jupiter swap decoder

Key takeaways

​A live stream, no decoding

​Decoding the binary data

​Understanding the transaction structure

​The proposal: everything inside message

​Transaction Header

​Account Keys Dictionary

​Protection Against Replay

​Instructions: The Actual Commands

​Signatures: Proof of Authorization

​Address Table Lookups

​How It All Connects: The Flow

​The execution: everything inside meta

​Basic execution information

​Advanced execution details

​Practical decoding patterns

​Complete example: Jupiter swap decoder

​Key takeaways

A live stream, no decoding

Decoding the binary data

Understanding the transaction structure

The proposal: everything inside message

Transaction Header

Account Keys Dictionary

Protection Against Replay

Instructions: The Actual Commands

Signatures: Proof of Authorization

Address Table Lookups

How It All Connects: The Flow

The execution: everything inside meta

Basic execution information

Advanced execution details

Practical decoding patterns

Complete example: Jupiter swap decoder

Key takeaways