Slot & Block Monitoring

Overview

Slot and block monitoring lets you watch Solana’s network in real-time. See when blocks are produced, track network health, and monitor transaction volume as it happens.

Start here first: Complete the Quickstart Guide to set up your stream manager.

What You Can Monitor

Slots
Full Blocks
Block Metadata

Watch the network heartbeatSlots are 400ms time windows. Watch them advance to see network health:

    const subscribeRequest: SubscribeRequest = {
      slots: {
        slotSubscribe: {
          filterByCommitment: false // Get all commitment levels
        }
      },
      commitment: CommitmentLevel.CONFIRMED
    };

What you’ll see:

Slot number
Parent slot
Status (processed, confirmed, or finalized)

Good for: Network health dashboards, timing analysis, detecting problems

Real Examples

Example 1: Basic Slot Monitor

Watch slots and track network performance:

import { StreamManager } from './yellowstone';
import { CommitmentLevel, SubscribeRequest } from "@triton-one/yellowstone-grpc";

async function monitorSlots() {
  const streamManager = new StreamManager(
    "https://grpc.solanatracker.io",
    process.env.GRPC_API_TOKEN || "your-api-key",
    handleSlotUpdate
  );

  const subscribeRequest: SubscribeRequest = {
    slots: {
      slotSubscribe: {
        filterByCommitment: false
      }
    },
    commitment: CommitmentLevel.PROCESSED
  };

  console.log("Starting slot monitoring...");
  await streamManager.connect(subscribeRequest);
}

const slotStats = {
  totalSlots: 0,
  lastSlot: 0,
  lastTimestamp: Date.now(),
  slotTimes: [] as number[],
  skippedSlots: 0
};

function handleSlotUpdate(data: any): void {
  if (data.slot) {
    const slot = data.slot;
    const currentTime = Date.now();
    
    slotStats.totalSlots++;
    
    console.log(`\n[Slot #${slotStats.totalSlots}]`);
    console.log(`  Slot Number: ${slot.slot}`);
    console.log(`  Parent Slot: ${slot.parentSlot}`);
    console.log(`  Status: ${slot.status.toUpperCase()}`);
    
    // Calculate timing if we have a previous slot
    if (slotStats.lastSlot > 0) {
      const slotDiff = slot.slot - slotStats.lastSlot;
      const timeDiff = currentTime - slotStats.lastTimestamp;
      
      if (slotDiff === 1) {
        // Normal progression
        slotStats.slotTimes.push(timeDiff);
        
        // Keep last 100 slots
        if (slotStats.slotTimes.length > 100) {
          slotStats.slotTimes.shift();
        }
        
        const avgSlotTime = slotStats.slotTimes.reduce((a, b) => a + b, 0) / slotStats.slotTimes.length;
        
        console.log(`  Time Since Last: ${timeDiff}ms`);
        console.log(`  Average (100 slots): ${avgSlotTime.toFixed(1)}ms`);
        
        // Alert on slow slots
        if (timeDiff > 800) {
          console.log(`  ⚠️  SLOW SLOT: Expected ~400ms, got ${timeDiff}ms`);
        }
      } else if (slotDiff > 1) {
        // Skipped slots
        const skipped = slotDiff - 1;
        slotStats.skippedSlots += skipped;
        console.log(`  ⚠️  SKIPPED ${skipped} SLOT(S)`);
        console.log(`  Total Skipped: ${slotStats.skippedSlots}`);
      }
    }
    
    slotStats.lastSlot = slot.slot;
    slotStats.lastTimestamp = currentTime;
    
    // Summary every 100 slots
    if (slotStats.totalSlots % 100 === 0) {
      printSlotSummary();
    }
  }
}

function printSlotSummary(): void {
  const avgSlotTime = slotStats.slotTimes.length > 0
    ? slotStats.slotTimes.reduce((a, b) => a + b, 0) / slotStats.slotTimes.length
    : 0;
  const skipRate = (slotStats.skippedSlots / slotStats.totalSlots * 100).toFixed(2);
  
  console.log(`\n=== Slot Summary ===`);
  console.log(`  Total Slots: ${slotStats.totalSlots}`);
  console.log(`  Skipped: ${slotStats.skippedSlots} (${skipRate}%)`);
  console.log(`  Average Slot Time: ${avgSlotTime.toFixed(1)}ms`);
  console.log(`  Expected: ~400ms per slot`);
}

monitorSlots().catch(console.error);

Example 2: Block Metadata Monitor

Track blocks and transaction volume:

async function monitorBlocks() {
  const streamManager = new StreamManager(
    "https://grpc.solanatracker.io",
    process.env.GRPC_API_TOKEN || "your-api-key",
    handleBlockMeta
  );

  const subscribeRequest: SubscribeRequest = {
    blocksMeta: {
      blockMetaSubscribe: {}
    },
    commitment: CommitmentLevel.CONFIRMED
  };

  console.log("Monitoring blocks...");
  await streamManager.connect(subscribeRequest);
}

const blockStats = {
  totalBlocks: 0,
  totalTransactions: 0,
  totalRewards: 0,
  highActivityBlocks: 0,
  blockTimes: [] as number[],
  lastBlockTime: 0
};

function handleBlockMeta(data: any): void {
  if (data.blockMeta) {
    const meta = data.blockMeta;
    blockStats.totalBlocks++;
    blockStats.totalTransactions += meta.transactionCount || 0;
    
    console.log(`\n[Block #${blockStats.totalBlocks}]`);
    console.log(`  Slot: ${meta.slot}`);
    console.log(`  Block Height: ${meta.blockHeight}`);
    console.log(`  Block Hash: ${meta.blockhash?.slice(0, 16)}...`);
    console.log(`  Transactions: ${meta.transactionCount || 0}`);
    
    // Track block timing
    if (meta.blockTime) {
      const blockTime = new Date(meta.blockTime * 1000);
      console.log(`  Block Time: ${blockTime.toISOString()}`);
      
      if (blockStats.lastBlockTime > 0) {
        const timeDiff = meta.blockTime - blockStats.lastBlockTime;
        blockStats.blockTimes.push(timeDiff);
        
        if (blockStats.blockTimes.length > 50) {
          blockStats.blockTimes.shift();
        }
        
        console.log(`  Time Since Last Block: ${timeDiff}s`);
      }
      
      blockStats.lastBlockTime = meta.blockTime;
    }
    
    // Track rewards
    if (meta.rewards && meta.rewards.length > 0) {
      const totalReward = meta.rewards.reduce((sum: number, r: any) => sum + (r.lamports || 0), 0);
      blockStats.totalRewards += totalReward;
      
      console.log(`  Block Rewards: ${(totalReward / 1e9).toFixed(6)} SOL`);
      console.log(`  Reward Count: ${meta.rewards.length}`);
      
      // Show top rewards
      const sortedRewards = [...meta.rewards]
        .sort((a: any, b: any) => (b.lamports || 0) - (a.lamports || 0))
        .slice(0, 3);
      
      sortedRewards.forEach((reward: any, idx: number) => {
        console.log(`    ${idx + 1}. ${reward.pubkey?.slice(0, 8)}... ${(reward.lamports / 1e9).toFixed(6)} SOL (${reward.rewardType || 'unknown'})`);
      });
    }
    
    // Flag high-activity blocks
    if (meta.transactionCount > 3000) {
      blockStats.highActivityBlocks++;
      console.log(`  🔥 HIGH ACTIVITY: ${meta.transactionCount} transactions`);
    }
    
    // Summary every 50 blocks
    if (blockStats.totalBlocks % 50 === 0) {
      printBlockSummary();
    }
  }
}

function printBlockSummary(): void {
  const avgTxPerBlock = blockStats.totalBlocks > 0
    ? (blockStats.totalTransactions / blockStats.totalBlocks).toFixed(1)
    : 0;
  const avgBlockTime = blockStats.blockTimes.length > 0
    ? (blockStats.blockTimes.reduce((a, b) => a + b, 0) / blockStats.blockTimes.length).toFixed(1)
    : 0;
  const totalRewardsSOL = (blockStats.totalRewards / 1e9).toFixed(4);
  
  console.log(`\n=== Block Summary ===`);
  console.log(`  Total Blocks: ${blockStats.totalBlocks}`);
  console.log(`  Total Transactions: ${blockStats.totalTransactions}`);
  console.log(`  Avg Tx/Block: ${avgTxPerBlock}`);
  console.log(`  High Activity Blocks: ${blockStats.highActivityBlocks}`);
  console.log(`  Avg Block Time: ${avgBlockTime}s`);
  console.log(`  Total Rewards: ${totalRewardsSOL} SOL`);
}

monitorBlocks().catch(console.error);

Example 3: Filtered Block Monitor

Watch blocks that contain specific program activity:

// Replace with programs you want to monitor
const TOKEN_PROGRAM = "TokenkegQfeZyiNwAJbNbGKPFXCWuBvf9Ss623VQ5DA";
const SYSTEM_PROGRAM = "11111111111111111111111111111111";

async function monitorFilteredBlocks() {
  const streamManager = new StreamManager(
    "https://grpc.solanatracker.io",
    process.env.GRPC_API_TOKEN || "your-api-key",
    handleFilteredBlock
  );

  const subscribeRequest: SubscribeRequest = {
    blocks: {
      filteredBlocks: {
        accountInclude: [TOKEN_PROGRAM, SYSTEM_PROGRAM], // Your programs here
        includeTransactions: true,
        includeAccounts: false,
        includeEntries: false
      }
    },
    commitment: CommitmentLevel.CONFIRMED
  };

  console.log("Monitoring filtered blocks...");
  await streamManager.connect(subscribeRequest);
}

const filteredStats = {
  totalBlocks: 0,
  totalTransactions: 0,
  successfulTx: 0,
  failedTx: 0,
  totalFees: 0,
  programCounts: new Map<string, number>()
};

function handleFilteredBlock(data: any): void {
  if (data.block) {
    const block = data.block;
    filteredStats.totalBlocks++;
    
    console.log(`\n[Filtered Block #${filteredStats.totalBlocks}]`);
    console.log(`  Slot: ${block.slot}`);
    console.log(`  Block Hash: ${block.blockhash?.slice(0, 16)}...`);
    console.log(`  Transactions in Block: ${block.transactions?.length || 0}`);
    
    if (block.transactions) {
      let blockTxCount = 0;
      let blockFees = 0;
      let successCount = 0;
      let failCount = 0;
      
      block.transactions.forEach((tx: any) => {
        blockTxCount++;
        filteredStats.totalTransactions++;
        
        const success = !tx.meta?.err;
        if (success) {
          successCount++;
          filteredStats.successfulTx++;
        } else {
          failCount++;
          filteredStats.failedTx++;
        }
        
        const fee = tx.meta?.fee || 0;
        blockFees += fee;
        filteredStats.totalFees += fee;
        
        // Track program usage
        const accountKeys = tx.transaction?.message?.accountKeys || [];
        const instructions = tx.transaction?.message?.instructions || [];
        
        instructions.forEach((ix: any) => {
          const programId = accountKeys[ix.programIdIndex];
          if (programId) {
            const count = filteredStats.programCounts.get(programId) || 0;
            filteredStats.programCounts.set(programId, count + 1);
          }
        });
      });
      
      console.log(`  Successful Tx: ${successCount}`);
      console.log(`  Failed Tx: ${failCount}`);
      console.log(`  Block Fees: ${(blockFees / 1e9).toFixed(6)} SOL`);
      console.log(`  Avg Fee: ${(blockFees / Math.max(blockTxCount, 1) / 1e9).toFixed(6)} SOL`);
      
      // Show program distribution in this block
      const programsInBlock = new Map<string, number>();
      block.transactions.forEach((tx: any) => {
        const keys = tx.transaction?.message?.accountKeys || [];
        const instructions = tx.transaction?.message?.instructions || [];
        
        instructions.forEach((ix: any) => {
          const programId = keys[ix.programIdIndex];
          if (programId) {
            const count = programsInBlock.get(programId) || 0;
            programsInBlock.set(programId, count + 1);
          }
        });
      });
      
      console.log(`  Programs Used:`);
      Array.from(programsInBlock.entries())
        .sort((a, b) => b[1] - a[1])
        .slice(0, 3)
        .forEach(([program, count]) => {
          const name = program === TOKEN_PROGRAM ? "Token Program"
            : program === SYSTEM_PROGRAM ? "System Program"
            : program.slice(0, 12) + "...";
          console.log(`    - ${name}: ${count} calls`);
        });
    }
    
    // Summary every 20 blocks
    if (filteredStats.totalBlocks % 20 === 0) {
      printFilteredSummary();
    }
  }
}

function printFilteredSummary(): void {
  const avgTxPerBlock = filteredStats.totalBlocks > 0
    ? (filteredStats.totalTransactions / filteredStats.totalBlocks).toFixed(1)
    : 0;
  const successRate = filteredStats.totalTransactions > 0
    ? (filteredStats.successfulTx / filteredStats.totalTransactions * 100).toFixed(1)
    : 0;
  
  console.log(`\n=== Filtered Block Summary ===`);
  console.log(`  Blocks Processed: ${filteredStats.totalBlocks}`);
  console.log(`  Total Transactions: ${filteredStats.totalTransactions}`);
  console.log(`  Avg Tx/Block: ${avgTxPerBlock}`);
  console.log(`  Success Rate: ${successRate}%`);
  console.log(`  Total Fees: ${(filteredStats.totalFees / 1e9).toFixed(4)} SOL`);
  
  console.log(`\n  Most Used Programs:`);
  Array.from(filteredStats.programCounts.entries())
    .sort((a, b) => b[1] - a[1])
    .slice(0, 5)
    .forEach(([program, count]) => {
      const name = program === TOKEN_PROGRAM ? "Token Program"
        : program === SYSTEM_PROGRAM ? "System Program"
        : program.slice(0, 12) + "...";
      console.log(`    ${name}: ${count} instructions`);
    });
}

monitorFilteredBlocks().catch(console.error);

Understanding the Data

Slot Data

  {
    slot: number;           // Which slot
    parentSlot: number;     // Previous slot  
    status: string;         // "processed", "confirmed", or "finalized"
  }

Slots happen every ~400msStatus levels:

Processed: Just happened
Confirmed: Majority of network agrees
Finalized: Can’t be undone

Block Metadata

  {
    slot: number;
    blockHeight: number;
    blockhash: string;
    parentBlockhash: string;
    blockTime: number;      // Unix timestamp
    transactionCount: number;
    rewards: Array<{
      pubkey: string;
      lamports: number;
      rewardType: string;   // "fee", "rent", "voting", "staking"
    }>;
  }

Block time: When the block was madeRewards: What validators earned

Full Block

  {
    slot: number;
    parentSlot: number;
    blockhash: string;
    previousBlockhash: string;
    transactions: Transaction[];  // All transactions
    accounts: AccountUpdate[];    // Account changes
    entries: Entry[];            // Entries (optional)
  }

Warning: Full blocks can be several MB

How Much Data?

Slot Monitoring

Very light

Minimal data usage
Real-time network pulse
Easy to process
Great for dashboards

Block Metadata

Medium

Moderate data usage
Block-level insights
Transaction counts
Good for analytics

Full Blocks

Heavy

High data usage
Everything included
Needs strong hardware
Use filters!

Filtered Blocks

Smart choice

Use accountInclude
Turn off what you don’t need
Focus on specific programs
Best balance

What You Can Build

Network Monitors
Analytics Tools
Sync Tools

Track network performance

Slot timing dashboards
Congestion alerts
Consensus tracking
Validator stats
Skip rate alerts

Common Problems

Missing Slots

Problem: You see gaps in slot numbersWhy it happens:

Connection dropped
Validator went down
Your code is too slow

Fix it:

Track gaps and alert
Add catch-up code
Check your connection

Too Much Data

Problem: Full blocks are overwhelmingFix it:

Use metadata instead
Add account filters
Turn off unnecessary data
Process async

Best Practices

Tips for production:

Start small - Use metadata before full blocks
Filter everything - Use accountInclude to reduce data
Watch timing - Track slots to spot problems
Handle gaps - Code for missing slots
Don’t block - Process data async
Match commitment - Pick the right level for your needs
Track yourself - Monitor your own performance
Set alerts - Get notified of problems

Common Questions

What's a slot?

A slot is a 400ms time window. Solana processes transactions in slots. One slot = one potential block (though some slots get skipped).

Should I use full blocks or metadata?

Start with metadata. It’s way lighter and has most of what you need. Only use full blocks if you need every transaction detail.

Why are some slots skipped?

Validators sometimes miss their turn to produce a block. This is normal and the network handles it automatically. A 5% skip rate is typical.

How big are full blocks?

A busy block can be several MB. That’s why filtering is important - you don’t want to download gigabytes of data you don’t need.

What's the difference between processed, confirmed, and finalized?

Processed (~400ms): Just happened, might change
Confirmed (~1 second): Supermajority agrees, probably won’t change
Finalized (~13 seconds): Locked in, can’t change

Next Steps

Entry Monitoring

Even more detailed monitoring

Account Monitoring

Watch specific accounts

Real Example

See it in action

Quickstart

Get started

Getting Started

Streaming Guides

Real-World Examples

Advanced Topics

Overview

What You Can Monitor

Real Examples

Example 1: Basic Slot Monitor

Example 2: Block Metadata Monitor

Example 3: Filtered Block Monitor

Understanding the Data

How Much Data?

Slot Monitoring

Block Metadata

Full Blocks

Filtered Blocks

What You Can Build

Common Problems

Best Practices

Common Questions

Next Steps

Entry Monitoring

Account Monitoring

Real Example

Quickstart

Getting Started

Streaming Guides

Real-World Examples

Advanced Topics

​Overview

​What You Can Monitor

​Real Examples

​Example 1: Basic Slot Monitor

​Example 2: Block Metadata Monitor

​Example 3: Filtered Block Monitor

​Understanding the Data

​How Much Data?

Slot Monitoring

Block Metadata

Full Blocks

Filtered Blocks

​What You Can Build

​Common Problems

​Best Practices

​Common Questions

​Next Steps

Entry Monitoring

Account Monitoring

Real Example

Quickstart

Overview

What You Can Monitor

Real Examples

Example 1: Basic Slot Monitor

Example 2: Block Metadata Monitor

Example 3: Filtered Block Monitor

Understanding the Data

How Much Data?

What You Can Build

Common Problems

Best Practices

Common Questions

Next Steps