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Transaction Trace API

GET /api/trace/:txHash​

Get detailed execution traces for a transaction, including all internal calls, events, and state changes.

Parameters​

Path Parameters​

  • txHash - The hash of the transaction to trace

Response​

{
  "success": true,
  "trace": {
    "hash": "0x...",
    "from": "0x...",
    "to": "0x...",
    "gasUsed": "34562",
    "status": true,
    "calls": [
      {
        "type": "CALL",
        "from": "0x...",
        "to": "0x...",
        "value": "0",
        "gas": "2300",
        "gasUsed": "2300",
        "input": "0x...",
        "output": "0x...",
        "calls": [] // Nested calls
      }
    ],
    "events": [
      {
        "address": "0x...",
        "topics": [
          "0x...", // Event signature
          "0x..." // Indexed parameter
        ],
        "data": "0x..." // Non-indexed parameters
      }
    ],
    "stateChanges": [
      {
        "address": "0x...",
        "slot": "0x...",
        "previousValue": "0x...",
        "newValue": "0x..."
      }
    ]
  }
}

Response Fields​

Trace Object​

  • hash - Transaction hash
  • from - Transaction sender
  • to - Target contract address
  • gasUsed - Total gas consumed
  • status - Transaction success status (true/false)

Call Object​

  • type - Type of call (CALL, STATICCALL, DELEGATECALL, CREATE, CREATE2)
  • from - Caller address
  • to - Target address
  • value - ETH value transferred
  • gas - Gas limit for this call
  • gasUsed - Gas consumed by this call
  • input - Input data
  • output - Return data
  • calls - Array of nested calls

Event Object​

  • address - Contract that emitted the event
  • topics - Array of indexed parameters
  • data - ABI-encoded non-indexed parameters

StateChange Object​

  • address - Contract address
  • slot - Storage slot
  • previousValue - Value before the transaction
  • newValue - Value after the transaction

Example Usage​

// Get trace for a transaction
const txHash = '0x123...';
const response = await fetch(`http://localhost:8000/api/trace/${txHash}`);
const data = await response.json();

if (data.success) {
  // Process trace data
  const { calls, events, stateChanges } = data.trace;
  
  // Analyze internal transactions
  calls.forEach(call => {
    console.log(`Call from ${call.from} to ${call.to}`);
    console.log(`Gas used: ${call.gasUsed}`);
  });
  
  // Process emitted events
  events.forEach(event => {
    console.log(`Event from ${event.address}`);
    console.log(`Topics: ${event.topics}`);
  });
  
  // Check state changes
  stateChanges.forEach(change => {
    console.log(`Contract ${change.address} storage slot ${change.slot} changed`);
    console.log(`From ${change.previousValue} to ${change.newValue}`);
  });
}

Error Responses​

{
  "success": false,
  "error": {
    "code": "ERROR_CODE",
    "message": "Error description"
  }
}

Common error codes:

  • TX_NOT_FOUND: Transaction hash not found
  • INVALID_TX_HASH: Invalid transaction hash format
  • TRACE_FAILED: Failed to generate trace