Implement the Operator Allowlist

To deploy a collection on Immutable zkEVM, you must implement the Operator Allowlist interface to protect your royalties and revenue in secondary market trading.

This tutorial will guide you through the steps required to ensure your collection is compliant with Immutable's Operator Allowlist.

💡WHO IS THIS FOR?

Developers who want to deploy a collection on Immutable zkEVM.

💡REQUIRED READING

Before continuing with this tutorial, please read our guide Operator Allowlist Explained which covers the importance of the Operator Allowlist, why it is mandatory and how it works.

Implementation Overview

The Operator Allowlist consists of 2 steps, only 1 of which is mandatory.

1. Asset Compliance (Mandatory)

💡Mandatory step

Implementing the Operator Allowlist is mandatory for all collections deployed on Immutable zkEVM.

Applies to: ERC-721 & ERC-1155 collections.

When required: For every NFT/SFT collection deployed on Immutable zkEVM.

Required action: Add interface to collection contract.

2. Utility Contract Privileges (Optional)

Applies to: Smart Contracts.

When required: Contracts necessitating approvals from collections or contracts facilitating transfers of assets between addresses.

Required action: Add smart contract to Immutable's registry via Hub.

Step 1: Asset Compliance (Mandatory)

Every NFT/SFT collection deployed on Immutable must be compliant to our Operator Allowlist specifications. Immutable streamlines this process by offering preset contracts which have the Operator Allowlist interface preconfigured. Should game studios choose to deploy their own custom collections, they must follow the instructions below to ensure their collection respects royalty fees across the platform.

Immutable Preset (Recommended)
Custom Collection

All Immutable provided preset contracts for NFT/SFT collections have the Operator Allowlist preconfigured, ensuring that your revenue from trades is protected across our platform.

If you have deployed or extended one of Immutable's preset contracts, either from Immutable Hub or manually, that's everything required to ensure compliance.

💡Explore Immutable Presets

Immutable recommends using our battle-tested, gas-optimised and ecosystem-wide compatible preset contracts that are OAL compliant out of the box instead of deploying a custom collection.

In cases where custom functionality is required, game studios can manually comply to the Operator Allowlist requirements by following the instructions below.

All collections on Immutable zkEVM are required to inherit OperatorAllowlistEnforced.sol and add necessary overrides to Approve and Transfer functions, allowing your collection to interact with the OperatorAllowlist. OperatorAllowlistEnforced includes the modifier functions to identify compliant smart contracts for approvals and transfers, ensuring the preservation of content creators' royalty fees and protocol fees in third-party marketplace transactions.

💡Mandatory Compliance

Failure to comply to Immutable's Operator Allowlist requirements will result in your NFT/SFT collection not being verified. All studio's in contract with Immutable are contractually obligated to implement the Operator Allowlist.

Add the Operator Allowlist to your custom collection

Example contracts using OpenZeppelin's ERC-721 and ERC-1155 standards with the OperatorAllowlistEnforced contract are provided below:

ERC721
ERC721 Upgradable
ERC1155
ERC1155 Upgradable

Below is an example ClashOfCatsERC721 contract that inherits our OperatorAllowlistEnforced:

// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.8.19;

import '@openzeppelin/contracts/token/ERC721/ERC721.sol';
import {Ownable} from '@openzeppelin/contracts/access/Ownable.sol';
import {OperatorAllowlistEnforced} from '@imtbl/contracts/contracts/allowlist/OperatorAllowlistEnforced.sol';

contract ClashOfCatsERC721 is ERC721, Ownable, OperatorAllowlistEnforced {
  constructor(
    string memory name,
    string memory symbol,
    address operatorAllowlist_
  ) ERC721(name, symbol) Ownable() {
    // OAL address is set in the constructor
    _setOperatorAllowlistRegistry(operatorAllowlist_);
  }

  // Overrides _approve function to include `validateApproval` modifier for OAL
  function _approve(
    address to,
    uint256 tokenId
  ) internal override(ERC721) validateApproval(to) {
    super._approve(to, tokenId);
  }

  // Overrides setApprovalForAll function to include `validateApproval` modifier for OAL
  function setApprovalForAll(
    address operator,
    bool approved
  ) public override(ERC721) validateApproval(operator) {
    super.setApprovalForAll(operator, approved);
  }

  // Overrides _transfer function to include `validateTransfer` modifier for OAL
  function _transfer(
    address from,
    address to,
    uint256 tokenId
  ) internal override(ERC721) validateTransfer(from, to) {
    super._transfer(from, to, tokenId);
  }
}

Below is an example ClashOfCatsERC721Upgradable contract that inherits our OperatorAllowlistEnforced:

pragma solidity 0.8.19;

import '@openzeppelin/contracts-upgradeable/token/ERC721/ERC721Upgradeable.sol';
import {Ownable} from '@openzeppelin/contracts/access/Ownable.sol';
import {OperatorAllowlistEnforced} from '@imtbl/contracts/contracts/allowlist/OperatorAllowlistEnforced.sol';

contract ClashOfCatsERC721Upgradable is
  ERC721Upgradeable,
  OperatorAllowlistEnforced
{
  function initialize(
    string memory name_,
    string memory symbol_,
    address operatorAllowlist_
  ) public initializer {
    __ERC721_init(name_, symbol_);
    // OAL address is set in the constructor
    _setOperatorAllowlistRegistry(operatorAllowlist_);
  }

  // Overrides approve function to include `validateApproval` modifier for OAL
  function approve(
    address to,
    uint256 tokenId
  ) public virtual override(ERC721Upgradeable) validateApproval(to) {
    super.approve(to, tokenId);
  }

  // Overrides setApprovalForAll function to include `validateApproval` modifier for OAL
  function setApprovalForAll(
    address operator,
    bool approved
  ) public virtual override(ERC721Upgradeable) validateApproval(operator) {
    super.setApprovalForAll(operator, approved);
  }

  // Overrides _safeTransfer function to include `validateTransfer` modifier for OAL
  function _safeTransfer(
    address from,
    address to,
    uint256 tokenId,
    bytes memory _data
  ) internal virtual override(ERC721Upgradeable) validateTransfer(from, to) {
    super._safeTransfer(from, to, tokenId, _data);
  }

  // Overrides transferFrom function to include `validateTransfer` modifier for OAL
  function transferFrom(
    address from,
    address to,
    uint256 tokenId
  ) public virtual override(ERC721Upgradeable) validateTransfer(from, to) {
    super.transferFrom(from, to, tokenId);
  }
}

Below is an example ClashOfCatsERC1155 contract that inherits our OperatorAllowlistEnforced:

// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.8.19;

import '@openzeppelin/contracts/token/ERC1155/ERC1155.sol';
import {Ownable} from '@openzeppelin/contracts/access/Ownable.sol';
import {OperatorAllowlistEnforced} from '@imtbl/contracts/contracts/allowlist/OperatorAllowlistEnforced.sol';

contract ClashOfCatsERC1155 is ERC1155, Ownable, OperatorAllowlistEnforced {
  constructor(
    string memory baseTokenURI,
    address operatorAllowlist_
  ) ERC1155(baseTokenURI) Ownable() {
    // OAL address is set in the constructor
    _setOperatorAllowlistRegistry(operatorAllowlist_);
  }

  // Overrides _safeTransferFrom function to include `validateTransfer` modifier for OAL
  function _safeTransferFrom(
    address from,
    address to,
    uint256 id,
    uint256 value,
    bytes memory data
  ) internal override validateTransfer(from, to) {
    super._safeTransferFrom(from, to, id, value, data);
  }

  // Overrides _safeBatchTransferFrom function to include `validateTransfer` modifier for OAL
  function _safeBatchTransferFrom(
    address from,
    address to,
    uint256[] memory ids,
    uint256[] memory values,
    bytes memory data
  ) internal override validateTransfer(from, to) {
    super._safeBatchTransferFrom(from, to, ids, values, data);
  }

  // Overrides setApprovalForAll function to include `validateApproval` modifier for OAL
  function setApprovalForAll(
    address operator,
    bool approved
  ) public override(ERC1155) validateApproval(operator) {
    super.setApprovalForAll(operator, approved);
  }
}

Below is an example ClashOfCatsERC1155Upgradable contract that inherits our OperatorAllowlistEnforced:

// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.8.19;

import '@openzeppelin/contracts-upgradeable/token/ERC1155/ERC1155Upgradeable.sol';
import {Ownable} from '@openzeppelin/contracts/access/Ownable.sol';
import {OperatorAllowlistEnforced} from './OperatorAllowlistEnforced.sol';

contract ClashOfCatsERC1155Upgradable is
  ERC1155Upgradeable,
  OperatorAllowlistEnforced
{
  function initialize(
    string memory uri_,
    address operatorAllowlist_
  ) public initializer {
    __ERC1155_init(uri_);
     // OAL address is set in the constructor
    _setOperatorAllowlistRegistry(operatorAllowlist_);
  }

  // Overrides _safeTransferFrom function to include `validateTransfer` modifier for OAL
  function _safeTransferFrom(
    address from,
    address to,
    uint256 id,
    uint256 value,
    bytes memory data
  ) internal override(ERC1155Upgradeable) validateTransfer(from, to) {
    super._safeTransferFrom(from, to, id, value, data);
  }

  // Overrides _safeBatchTransferFrom function to include `validateTransfer` modifier for OAL
  function _safeBatchTransferFrom(
    address from,
    address to,
    uint256[] memory ids,
    uint256[] memory values,
    bytes memory data
  ) internal override(ERC1155Upgradeable) validateTransfer(from, to) {
    super._safeBatchTransferFrom(from, to, ids, values, data);
  }

  // Overrides setApprovalForAll function to include `validateApproval` modifier for OAL
  function setApprovalForAll(
    address operator,
    bool approved
  ) public override(ERC1155Upgradeable) validateApproval(operator) {
    super.setApprovalForAll(operator, approved);
  }
}

Operator Allowlist Checklist

Here is a simple collection operator allowlist checklist you should follow to ensure your game has no delays at launch:

Have you imported OperatorAllowlistEnforced.sol?
Have you implemented the allowlist check on transfers?
Have you implemented the allowlist check on approvals?

Operator Allowlist values

If you manually deploy one of Immutable's preset contracts or your own custom contract that implements the Operator Allowlist, you must set the operatorAllowlist parameter in the constructor correctly for the network you're deploying to. The table below details the values required for Immutable zkEVM Testnet and Mainnet.

Chain Name	Chain ID	Operator Allowlist Address
`imtbl-zkevm-testnet`	eip155:13473	0x6b969FD89dE634d8DE3271EbE97734FEFfcd58eE
`imtbl-zkevm-mainnet`	eip155:13371	0x5F5EBa8133f68ea22D712b0926e2803E78D89221

Step 2: Utility Contract Privileges (Optional)

💡Approval for additional privileges

Please note that only partners under contract with Immutable can be approved for additional privileges at this time (i.e. be added to Immutable's Operator Allowlist registry).

Utility smart contracts that perform a subset of actions, that are not settlement contract, will need to be added to Immutable's Operator Allowlist registry to function as intended. This registration process is managed through your Hub account.

This step is not required for all smart contracts so please read this section carefully to understand if it applies to you.

Which smart contracts need elevated privileges?

If your utility smart contract performs the following actions, you will need to request for elevated privileges (i.e. be added to the Operator Allowlist):

Contracts necessitating approvals from collections.
Contracts facilitating the asset transfers of ERC721 or ERC1155 assets.

Examples of the above:

Multi-caller contracts that bundle transactions
Crafting contracts
Primary sales contracts
Reward distribution contracts
Auction contracts
Rental contracts
Lending contracts

Ineligible utility smart contracts

The following smart contracts are ineligible for being added to the Operator Allowlist.

Settlement contracts (excluding those provided by Immutable)
Orderbook contracts that could fragment liquidity from Immutable's Global Orderbook

💡Policy violations

Immutable reserves the right to remove elevated privileges for any contracts found in violation of the stated policy above. If you are not sure whether your contract adheres to this policy, please reach out to your Immutable contact for clarification.

Requirements

Game studios must meet the following criteria to be able to submit a request for elevated privileges:

Game studios must have a contract with Immutable.
Contract must be verified in block explorer so Immutable can review your contract's code. This is for both Testnet and Mainnet.
Contract has previously been approved for elevated privileges (i.e. added to Operator Allowlist registry) on Testnet and tested thoroughly, prior to proceeding with Mainnet.
- Note: All Testnet requests are auto-approved to expedite game integrations.
Contract does not violate Immutable's ineligibility policy outlined above.

Submitting proxy contracts

Upgradable Contracts

Immutable supports adding proxy contracts to the Operator Allowlist registry. The proxy contract will require being added to the Operator Allowlist. Both proxy and the implementation contract that the proxy references will need to be verified in block explorer to be approved by Immutable.

Smart Contract Wallets

As smart contract wallets are deployed as proxy contracts with a specific implementation contract module, they will need their implementation contract approved as well. Both proxy and the implementation contract that the proxy references will need to be verified in block explorer to be approved by Immutable.

How do I submit a request for elevated smart contract privileges?

Log into Immutable Hub
Verify your contract via Immutable's explorer by following our smart contract verification tutorial.
Link your smart contract by clicking Link Contract on the "Contracts" page in Immutable Hub.
Go to the contract details page of the contract that you want to be added to OAL. Hit the "Add to OAL" button and follow the application prompts.

Processing time for elevated smart contract privilege requests

Immutable will process these requests as quickly as possible.

Testnet additions are processed instantly.
Mainnet additions require at least 48 hours for processing. Timely submission of requests is advised to avoid launch delays for your game.

Interface

Please refer to the OperatorAllowlist.sol interface for information on specific methods.

Implement the Operator Allowlist

Implementation Overview​

1. Asset Compliance (Mandatory)​

2. Utility Contract Privileges (Optional)​

Step 1: Asset Compliance (Mandatory)​

Add the Operator Allowlist to your custom collection​

Operator Allowlist Checklist​

Operator Allowlist values​​

Step 2: Utility Contract Privileges (Optional)​

Which smart contracts need elevated privileges?​

Ineligible utility smart contracts​

Requirements​

Submitting proxy contracts​​

Upgradable Contracts​

Smart Contract Wallets​

How do I submit a request for elevated smart contract privileges?​​

Processing time for elevated smart contract privilege requests​​

Interface​