Implementations of a proxy contract

Open the proxy on its entity page →

The implementations a proxy contract has been observed delegating to, newest first — found in its EIP-1167 bytecode, its EIP-1967 implementation or beacon slot, its OpenZeppelin v1 slot, or slot 0 of a Safe proxy — each with the blocks it was seen at and whether it has since been replaced.

GET https://tracefast.xyz/api/v1/chains/1/contracts/{address}/proxy

Access — an API key on the Enriched Data 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_contract_proxy on the MCP server. Stable — see stability.

chains/1 is a literal: other chain ids answer 404 chain_not_supported. The method takes no query parameters — an unknown one is refused rather than ignored.

What it covers, and what it does not

• Five ways a pointer is found: EIP-1167 minimal-proxy bytecode, the EIP-1967 implementation slot, the EIP-1967 beacon slot, the OpenZeppelin v1 slot, and slot 0 of a Safe proxy — the singleton the Safe delegates to. A proxy that keeps its pointer anywhere else is not covered.
• An empty list is not "not a proxy". It means no pointer was observed — the address may be an ordinary contract, an account, or a proxy of a kind listed nowhere above. Any address answers 200; there is no 404 for an address without code.
• For a beacon proxy, implementation is the beacon, not the logic contract. The logic the beacon handed out over time is on the same row, in beacon — see a beacon proxy.

Response

200 application/json, USDC — four implementations over its history, the newest first. Two are shown:

{
  "data": {
    "chainId": 1,
    "address": "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48",
    "implementations": [
      {
        "implementation": "0x43506849d7c04f9138d1a2050bbf3a0c054402dd",
        "source": "storage_oz_v1",
        "proxyFamily": "unknown",
        "confidence": 1,
        "firstSeenBlock": 18963716,
        "lastSeenBlock": 18963716,
        "slot": "0x7050c9e0f4ca769c69bd3a8ef740bc37934f8e2c036e5a723fd8ee048ed3f8c3",
        "isSelfDelegation": false,
        "supersededBy": null,
        "slotLastEvent": {
          "kind": "upgrade",
          "blockNumber": 18963716,
          "txHash": "0xae3ad89e569f27d47a8a02999a6d937c12aaa6bc50e66650e7cbd3244bde9951"
        }
      },
      {
        "implementation": "0xa2327a938febf5fec13bacfb16ae10ecbc4cbdcf",
        "source": "storage_oz_v1",
        "proxyFamily": "unknown",
        "confidence": 1,
        "firstSeenBlock": 12317814,
        "lastSeenBlock": 12317814,
        "slot": "0x7050c9e0f4ca769c69bd3a8ef740bc37934f8e2c036e5a723fd8ee048ed3f8c3",
        "isSelfDelegation": false,
        "supersededBy": "0x43506849d7c04f9138d1a2050bbf3a0c054402dd",
        "supersededByBlock": 18963716,
        "slotLastEvent": {
          "kind": "upgrade",
          "blockNumber": 18963716,
          "txHash": "0xae3ad89e569f27d47a8a02999a6d937c12aaa6bc50e66650e7cbd3244bde9951"
        }
      }
    ]
  },
  "meta": {
    "chain": "ethereum",
    "timestamp": 1789047625464,
    "cached": false,
    "docs": "https://docs.tracefast.xyz/api/contract-proxy"
  }
}

data

An implementation

slotLastEvent.kind names what the write did: upgrade — an address was written to the slot, the first one included, as in the example; cleared — the slot was emptied; unset — zero was written, removing the pointer.

supersededBy has three states

Each means something different, and a client has to tell them apart:

On a beacon row supersededBy speaks only of the proxy's beacon slot: an address means the proxy was switched to another beacon. It is never null there, because the logic changes inside the beacon, not in the proxy — those changes are in beacon.implementations.

A Safe's singleton follows the same lifecycle as an EIP-1967 slot. The Safe at 0x1db92e2eebc8e0c075a02bea49a2935bcd2dfcf4 answers two rows with source: storage_safe_singleton: 0x34cfac64… with supersededBy 0xbdd077f6… at block 21895238, and 0xbdd077f6… with supersededBy: null — the singleton in use now.

A beacon proxy

A beacon proxy reads its logic from a beacon, and the beacon can be upgraded for all its proxies at once. The row of such a proxy names the beacon in implementation, and beacon carries the logic history:

{
  "implementation": "0x31946680978cefb010e5f5fa8b8134c058cba7dc",
  "source": "storage_beacon",
  "proxyFamily": "none",
  "confidence": 0,
  "firstSeenBlock": 13436882,
  "lastSeenBlock": 13436882,
  "slot": "0xa3f0ad74e5423aebfd80d3ef4346578335a9a72aeaee59ff6cb3582b35133d50",
  "isSelfDelegation": false,
  "slotLastEvent": {
    "kind": "upgrade",
    "blockNumber": 13436882,
    "txHash": "0x65f21bcbfa041792caf56dbf156496cd0ee07612511c0c38e03eeb2f369570bf"
  },
  "beacon": {
    "state": "proven",
    "provenFromBlock": 12545235,
    "completeThroughBlock": 26236750,
    "implementations": [
      { "implementation": "0x33886c99a834096f4a07ea1857d6819ca786e8b7", "startBlock": 15542644 },
      { "implementation": "0x708555f88aa9249e1d81d1acbcfd6e9cebd781e5", "startBlock": 15540580, "endBlock": 15542643 }
    ]
  }
}

The proxy 0x2279f53a28ee4c24efe1578d4dc072e5dc0f2a6a, shortened: its beacon handed out 43 logic contracts since block 12545235. The one in use now is the first entry, the one without endBlock.

A beacon whose logic could not be established answers "beacon": { "state": "not_proven", "implementations": [] } — for example the beacon behind 0xcdc974efcebe0eea0dc53e6e732321e405ca3703.

What proxies are and why they are used: ethereum.org — upgrading smart contracts.

Errors

This method has no errors of its own.

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

• One contract — the proxy pattern detected in the code
• Bytecode of a contract — the code of an implementation
• Function selectors of a contract — what an implementation can be called with
• Contracts on the entity page — proxy relationships, read in the app

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