Execution trace of a transaction

See this trace in TraceFast →

Every call frame a transaction executed, in the order it ran: the caller and target of each, the kind of call, the value and gas it moved, its own outcome, and why it reverted where it did. A delegatecall names both the storage context and the address whose code ran — which is what makes a proxy call readable. create and create2 frames name the address they deployed. For the EVM background, see the EVM on ethereum.org.

This method answers the whole tree in one response, up to 1 000 frames. For a larger tree, or when you need every frame's calldata and the event logs it emitted, page through call frames of a transaction.

GET https://tracefast.xyz/api/v1/chains/1/traces/{hash}

Access — an API key on the Investigation plan or higher (plans), or no key at all: pay per call with x402 at the same path on https://mpp.tracefast.xyz/api/v1, at the price its 402 states. As a tool for AI agents: get_transaction_trace on the MCP server. Stable — see stability.

chains/1 is a literal: the method serves Ethereum mainnet data. Other chain ids answer 404 chain_not_supported. There are no other parameters — an unknown one is refused rather than ignored.

What it covers, and what it does not

• At most limit frames — 1 000 by default and at most. framesTruncated says when the tree is larger; frames is then its first frames in pre-order. A clipped tree never claims to be the whole one. Call frames, paged walks larger trees.
• Each frame has its own outcome. A frame can revert while the transaction succeeds, when a caller catches the revert. status is the frame's, not the transaction's.
• A trace that is not available yet is refused, never answered empty. Traces trail the chain by minutes to hours, sometimes longer. A transaction in a block the traces have not reached answers 422 block_not_available with reason: coverage_gap and the last block traces are available for, maxAvailableBlock. That says nothing about the transaction's outcome — ask again later; the outcome itself is on one transaction.
• Traces start at block 2 675 000. Older transactions are refused by name (422), not answered with an incomplete tree.
• Calldata is opt-in and clipped. inputHead and outputHead are the first 260 bytes; inputSize and outputSize are the full lengths.

Response

200 application/json, here with ?includeCalldata=true — a USDC transfer through its proxy:

{
  "data": {
    "hash": "0xc41b41fb1c3eea59ea87b9e90edf476fb202e8daf02f19f469cdf497adbc76e0",
    "blockNumber": 25920000,
    "txIndex": 3,
    "frameCount": 2,
    "totalFrameCount": 2,
    "framesTruncated": false,
    "frames": [
      {
        "order": 0,
        "depth": 1,
        "callPath": "0000",
        "callType": "call",
        "from": "0x978e75381d64fb18af7112e42fa76a211a773456",
        "to": "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48",
        "valueWei": "0",
        "gas": "78392",
        "gasUsed": "40652",
        "inputSelector": "0xa9059cbb",
        "status": "success",
        "revertDecodeStatus": "absent",
        "codeAddress": "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48",
        "inputHead": "0xa9059cbb000000000000000000000000f9dec5642e2b51ba67c695144d3360fab966f5a30000000000000000000000000000000000000000000000000000000029ba1944",
        "inputSize": 68,
        "outputHead": "0x0000000000000000000000000000000000000000000000000000000000000001",
        "outputSize": 32
      },
      {
        "order": 1,
        "depth": 2,
        "callPath": "00000000",
        "parentPath": "0000",
        "callType": "delegatecall",
        "from": "0x978e75381d64fb18af7112e42fa76a211a773456",
        "to": "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48",
        "valueWei": "0",
        "gas": "70036",
        "gasUsed": "33363",
        "inputSelector": "0xa9059cbb",
        "status": "success",
        "revertDecodeStatus": "absent",
        "codeAddress": "0x43506849d7c04f9138d1a2050bbf3a0c054402dd",
        "inputHead": "0xa9059cbb000000000000000000000000f9dec5642e2b51ba67c695144d3360fab966f5a30000000000000000000000000000000000000000000000000000000029ba1944",
        "inputSize": 68,
        "outputHead": "0x0000000000000000000000000000000000000000000000000000000000000001",
        "outputSize": 32
      }
    ]
  },
  "meta": {
    "chain": "ethereum",
    "timestamp": 1789063644200,
    "cached": false,
    "asOfBlock": 25920000,
    "docs": "https://docs.tracefast.xyz/api/trace"
  }
}

Read the pair: frame 0 calls the USDC proxy; frame 1 is the proxy's delegatecall. Its to stays the proxy — the storage that changes — while codeAddress is the implementation whose code ran.

data

A frame — position and call

A frame — outcome

A frame — with includeCalldata=true

Errors

A transaction the traces have not reached yet:

{
  "error": {
    "code": "block_not_available",
    "message": "the trace of block 25948674 is not available yet: it is available up to block 25925232. This says nothing about the transaction's outcome — retry later, or ask about a transaction at or below block 25925232.",
    "details": {
      "reason": "coverage_gap",
      "maxAvailableBlock": 25925232,
      "coverageGapFromBlock": 25925233
    },
    "requestId": "01a08c80-5ef3-76f1-acaf-fa7d749068cb"
  }
}

Malformed input, unknown parameters and the key check's 401/403/429 are the same for every method — see conventions and API keys.

Related pages

• Call frames of a transaction, paged — trees over 1 000 frames, calldata on every frame, the logs each frame emitted
• Why a transaction reverted — only the failed frames, with error names
• Storage writes of a transaction — what each frame wrote to contract storage
• One transaction — the transaction's own outcome
• Implementations of a proxy contract — the implementations behind a delegatecall
• Transactions: Trace — the same call tree in the app

Last updated 22 Oct 2026, 08:06 UTC · verified against TraceFast v1.0.261 · Markdown