Add feesOnTop to Orders

feesOnTop (referral fees) are fees paid to an individual or entity for facilitating a sale. For example, you can set feesOnTop on your marketplace built with Reservoir's SDK, ReservoirKit, or APIs for all orders purchased on your platform. This applies to orders coming from OpenSea or other aggregated marketplaces.

Using the Reservoir SDK

To add feesOnTop, you can follow these steps for the buyToken method:

  1. First, make sure you have installed and configured the Reservoir SDK. If you haven't, you can refer to the Reservoir SDK (JS/TS/Node) here.

  2. Next, when executing a buy or sell order, you can include the feesOnTop in the options (formatted as feeRecipient:feeAmount). The feesOnTop parameter is an array of objects, each containing a recipient (the address receiving the referral fee) and a fixed fee in wei.

Here's a sample code snippet for adding feesOnTop when buying a token:

import { getClient, Execute } from "@reservoir0x/reservoir-sdk";
import { createWalletClient, http } from 'viem'


address = "0x8ba1f109551bD432803012645Ac136ddd6000000"
signer = createWalletClient({
  account: address,
  transport: http()

  items: [{ token: "0xbc4ca0eda7647a8ab7c2061c2e118a18a936f13d:1", quantity: 1 }],
  options: {
    feesOnTop: [
  onProgress: (steps: Execute['steps']) => {

This example demonstrates how to add feesOnTop when buying a token using the Reservoir SDK. The feesOnTop parameter is included in the options object when calling the buyToken method.

Using the ReservoirKit

You can add feesOnTopBps or feesOnTopFixed in ReservoirKit. This is for the BuyModal. Please note that feesOnTopBps will take precedence over the feesOnTopFixed. The feesOnTopFixed is in the atomic unit of the listing currency (e.g. wei is used for ETH). List of fees (formatted as feeRecipient:feeAmount) to be taken when filling. Unless overridden via the currency param, the currency used for any fees on top matches the buy-in currency detected by the backend.

Below is a sample configuration for the BuyModal. Note that an array of referrers and fees cannot be passed, please see the SDK or API to pass an array.

import { BuyModal } from '@reservoir0x/reservoir-kit-ui'

      Buy Token
  onPurchaseComplete={(data) => console.log('Purchase Complete')}
  onPurchaseError={(error, data) => console.log('Transaction Error', error, data)}
  onClose={(data, stepData, currentStep) => console.log('Modal Closed')}


Using the Reservoir API


We recommend using Reservoir SDK

Reservoir SDK includes helpers that abstract the process of iterating through steps, and returning callbacks that can be used to update your UI.

To set a feesOnTop for an order, input in the feesOnTop field (formatted as feeRecipient:feeBps) as an option for the /execute/buy API. In the example, the feesOnTop parameter is an array of objects, each containing a recipient (the address receiving the referral fee) and a fixed fee in wei.

curl --request POST \
     --url \
     --header 'accept: */*' \
     --header 'content-type: application/json' \
     --header 'x-api-key: demo-api-key' \
     --data '
  "items": [
      "quantity": 1,
      "token": "0xbc4ca0eda7647a8ab7c2061c2e118a18a936f13d:1"
  "onlyPath": false,
  "normalizeRoyalties": false,
  "allowInactiveOrderIds": false,
  "feesOnTop": [
  "partial": false,
  "skipBalanceCheck": false,
  "excludeEOA": false,
  "taker": "0x8ba1f109551bD432803012645Ac136ddd64DBA72"