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Custom Webhook Filters

Understand what filters are available for Custom Webhooks and how to use them

Alchemy's Custom Webhooks allow you to access any on-chain activity while also precisely defining filters to control your data pipelines. With Alchemy's filters, you are able to set up logic for when you want blockchain data, whether that's for token movement, transactions of interest, or full blocks of data! Additionally, they allow you to easily filter down the data to exactly what you need, saving you on data ingestion costs and reducing infrastructure overhead.

To get started with the filters head over to the Custom Webhook playground and test them out!

Alchemy's Custom Webhooks currently feature filters on 3 types of on-chain data:

  • Events/Logs
  • External Transactions
  • Internal Transactions (Debug trace calls)

Event/Log Filters

Custom Webhook log/event filters leverage the same semantics as a traditional eth_getLogs RPC call. In particular, we maintain the 2 key fields that eth_getLogs accepts to query for events of interest: an address field and a topics field

In particular, Custom Webhook log GraphQL objects accept a BlockLogsFilterCriteria filter which is comprised of the following objects:

  • addresses: [Address!]
    Addresses accepts an array of strings which map to either a single contract address or a list of addresses from which logs should originate. If this list is empty, results will not be filtered by address.
  • topics: [[Bytes32!]!]
    Array of 32 Bytes DATA topics. Topics are order-dependent. Each topic can also be an array of DATA with "or" options.

If you're not familiar with how topic filters work for eth_getLogs, here's an article to get you up to speed.

📘

A note on specifying topic filters within Custom Webhooks:

A transaction with topics will be matched by the following topic filters:

  • [] “anything”
  • [A] “A in first position (and anything after)”
  • [[], [B]] “anything in first position AND B in second position (and anything after)”
  • [A, B] “A in first position AND B in second position (and anything after)”
  • [[A, B], [A, B]] “(A OR B) in first position AND (A OR B) in second position (and anything after)”

Specifying Addresses within Custom Webhook Event Filters

Let's investigate an example log filter together! In this snippet, we only define a single address of interest, the Bored Ape NFT contract 0xBC4CA0EdA7647A8aB7C2061c2E118A18a936f13D. In this example, we set our filter so that we return logs/events only associated with the Bored Ape NFT contract.

# Get all logs emitted by the Bored Ape NFT contract in block 0x4a4d98f90439daaf082642dfbdd0f7b9a36749484582fb3d3e03bd4583da337a

{
  block(hash: "0x4a4d98f90439daaf082642dfbdd0f7b9a36749484582fb3d3e03bd4583da337a") {
    logs(filter: {addresses: ["0xBC4CA0EdA7647A8aB7C2061c2E118A18a936f13D"], topics: []}) {
      topics
      data
    }
  }
}

📘

NOTE:

In the case where we would want apply the same filter across a list of contracts, we could simply add more addresses to the address list part of filter!

Specifying Topics within Custom Webhook Event Filters

Let's investigate an example topc filter together! In this snippet, we only define a single topic of interest, the transfer event with a kek hash of 0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef. In this example, we set our filter so that we return logs/events only associated with the transfer event

# Get all logs associated with a transfer event  in block 0x4a4d98f90439daaf082642dfbdd0f7b9a36749484582fb3d3e03bd4583da337a

{
  block(hash: "0x4a4d98f90439daaf082642dfbdd0f7b9a36749484582fb3d3e03bd4583da337a") {
    logs(filter: {addresses: [], topics: ["0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef"]}) {
      topics
      data
    }
  }
}

External Transaction Filters

Custom Webhook external transaction filters allow developers to filter on the to and from addresses associated with each external transaction!

📘

What is an external transaction?

An external transaction refers to a transaction that is initiated by an external account on the Ethereum network. It involves sending a request to modify the state of the Ethereum blockchain, such as transferring Ether (the native cryptocurrency of Ethereum) or interacting with a smart contract.

In particular, Custom Webhook log GraphQL objects accept a BlockTransactionsFilterCriteria filter which is comprised of the following fields!

  • from: [Address!]
    The sending party of a transaction
  • to: [Address!]
    The receiving party of a transaction

A transaction from the BlockTransactionsFilterCriteria will match if it has a from address that is in the list of from addresses AND a to address that is in the list of to addresses provided. Missing or empty lists will be treated as wildcards and will return a match.

Specifying from addresses within Custom Webhook Transaction Filters

Let's investigate an example transaction filter together! In this snippet, we only define a single from address of interest 0xc83dad6e38BF7F2d79f2a51dd3C4bE3f530965D6 so that Alchemy sends out webhook emissions only associated with 0xc83dad6e38BF7F2d79f2a51dd3C4bE3f530965D6

# Filter for transactions originating from 0xc83dad6e38BF7F2d79f2a51dd3C4bE3f530965D6
{
  block(hash: "0x49c8fd41516ed8d8ba871c0dadaddb0928d7d03d4de569b2537343080f48c618") {
    hash
    number
    timestamp
    transactions(filter:
      {addresses: [
				{from: ["0xc83dad6e38BF7F2d79f2a51dd3C4bE3f530965D6"]}
      ]}
    ) {
      from {
        address
      },
      to {
        address
      }
      hash,
      value
      gas
      status
    }
  }
}

Specifying to within Custom Webhook Transaction Filters

Let's investigate an example transaction filter together! In this snippet, we only define a single to address 0x388C818CA8B9251b393131C08a736A67ccB19297 of interest so that Alchemy sends out webhook emissions only associated with transactions sent to 0x388C818CA8B9251b393131C08a736A67ccB19297

# Filter for transactions sent to 0x388C818CA8B9251b393131C08a736A67ccB19297
{
  block(hash: "0x49c8fd41516ed8d8ba871c0dadaddb0928d7d03d4de569b2537343080f48c618") {
    hash
    number
    timestamp
    transactions(filter:
      {addresses: [
				{to: ["0x388C818CA8B9251b393131C08a736A67ccB19297"]}
      ]}
    ) {
      from {
        address
      },
      to {
        address
      }
      hash,
      value
      gas
      status
      }
    }
  }

Specifying from & to within Custom Webhook Transaction Filters

Let's investigate an example transaction filter together! In this snippet, we only define a single to address 0xeb83e695adcac2e83f290d2d2815fc58e6491d7a and a from address 0x29469395eaf6f95920e59f858042f0e28d98a20b so that Alchemy sends out webhook emissions only associated with that from and to configuration.

{
  block(hash: "0x49c8fd41516ed8d8ba871c0dadaddb0928d7d03d4de569b2537343080f48c618") {
    hash
    number
    timestamp
    transactions(filter:
      {addresses: [
        {from: ["0xeb83e695adcac2e83f290d2d2815fc58e6491d7a"]},
				{to: ["0x29469395eaf6f95920e59f858042f0e28d98a20b"]}
      ]}
    ) {
      from {
        address
      },
      to {
        address
      }
      hash,
      value
      gas
      status
      }
    }
  }

Internal Transaction (Debug trace calls) Filters (BETA)

📘

What is an internal transaction?

An internal transaction refers to a transaction that is triggered as a result of the execution of a smart contract. Unlike external transactions that are initiated by external accounts, internal transactions occur within the context of a specific smart contract and are not directly initiated by external users or applications.

Similar to external transactions, Custom Webhook log GraphQL objects accept a BlockCallTracesFilterCriteria filter which is comprised of the following fields!

  • from: [Address!]
    The sending party of a transaction
  • to: [Address!]
    The receiving party of a transaction

A transaction from the BlockCallTracesFilterCriteria will match if it has a from address that is in the list of from addresses AND a to address that is in the list of to addresses provided. Missing or empty lists will be treated as wildcards and will return a match.

Specifying from addresses within Custom Webhook Internal Transaction Filters

# Filter for internal transactions originating from 0x5c43B1eD97e52d009611D89b74fA829FE4ac56b1
{
  block {
    number
    callTracerTraces (filter: 
		 {addresses: [
        {from: ["0x5c43B1eD97e52d009611D89b74fA829FE4ac56b1"], to: []}
      ]}
    ){
      from {
        address
      }
      to {
        address
      }
      type
      input
      output
      value
      gas
      gasUsed
      input
      output
      error
      revertReason
      subtraceCount
      traceAddressPath
    }
  }
}

Specifying to addresses within Custom Webhook Internal Transaction Filters

# Filter for internal transactions going to  0x5c43B1eD97e52d009611D89b74fA829FE4ac56b1
{
  block {
    number
    callTracerTraces (filter: 
		 {addresses: [
        {from: [], to: ["0x5c43B1eD97e52d009611D89b74fA829FE4ac56b1"]}
      ]}
    ){
      from {
        address
      }
      to {
        address
      }
      type
      input
      output
      value
      gas
      gasUsed
      input
      output
      error
      revertReason
      subtraceCount
      traceAddressPath
    }
  }
}

Specifying from & to within Custom Webhook Internal Transaction Filters

{
  block {
    number
    callTracerTraces (filter: 
		 {addresses: [
        {from: ["0x29469395eaf6f95920e59f858042f0e28d98a20b"], to: ["0x5c43B1eD97e52d009611D89b74fA829FE4ac56b1"]}
      ]}
    ){
      from {
        address
      }
      to {
        address
      }
      type
      input
      output
      value
      gas
      gasUsed
      input
      output
      error
      revertReason
      subtraceCount
      traceAddressPath
    }
  }
}
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