Automated NFT airdrop ( URI Remit )

June 10, 2025 at 10:01 PM

Updated June 11, 2025 at 08:53 PM

URI Remit Hook Tutorial

After some encouragement from Satish, I will be sharing some details of the amazing hooks I've been creating here on xpert.page. By publishing these examples and putting them to use on Xahau Mainnet, I hope to encourage others to #GetHooked and explore their own use cases for this account layer of programmability.

The first hook I'll share is the URI Remit Hook, which mints and sends back an NFT whenever an incoming payment is received. This is a simplified version of the URI-Token-Remit created by @Cbot_Xrpl, designed for use as a thank-you card on my daughters xpert.page.

Getting Started

Automated NFT Airdrop

To keep things as simple as possible, we'll use three tools: Pinata IPFS, XRPLWin, and Hex Visualizer. This tutorial was created on testnet, but when you're ready to deploy to mainnet, the only changes required will be the Hook Hash and possibly the account you're installing it on.

Tools and Resources

Wallet Generator: https://test.xahauexplorer.com/create/
Wallet Funding: https://test.xahauexplorer.com/en/faucet
Hook Hashes:
- Testnet: 8F9F3EAC7945092D65F26D96BDC8E336F95F44BBFB381F18924E58A69DF62DD2
- Mainnet: 2D282A0F475B79510BE5B6CAEA2C655571A6B229BC36F8EB7B5E2650BE2EA93F

Required Tools

Pinata IPFS - https://app.pinata.cloud
This service will host our image files and metadata. The free tier supports up to 500 files, with competitive options for expanding collections in the future.
XRPLWin - https://testnet.xrplwin.com/
XRPLWin's hook dashboards are exceptional, offering tools to take your testnet project to mainnet. It's also great for debugging on testnet and managing hooks on mainnet.
Hex Visualizer - https://transia-rnd.github.io/xrpl-hex-visualizer/
This tool converts strings into the correct hex formats required for our parameters. If your hook compilation fails, double-check your hex codes here.

Pinata Setup

Setting up files for the remit hook can be tricky, as the hook expects a predetermined URI length. The best approach is to host the images first, then create a folder of JSON files referencing them.

Pinata Fileserver

Sign up for Pinata and select the free tier. Upload the images you want to use. Once uploaded, you'll receive a CID (Content Identifier), which uniquely identifies each image.

Create a new folder and download the JSON template from HERE. Customize the JSON file with unique identifiers and update the image CID path to match the CID of the uploaded image. Create as many files as needed, ensuring consistent file name lengths (e.g., 000001.json, 000002.json, 000003.json).

Example JSON:

{
  "name": "HandyHooks - Thank you remit",
  "description": "This is a thank you gift for your donation through the xpert.page platform, we appreciate your support",
  "image": "ipfs://YOUR_IMAGE_CID_GOES_HERE",
  "external_link": "https://xpert.page/handy_4ndy",
  "attributes": [
    {
      "trait_type": "Message",
      "value": "Thank you for your support, we appreciate it!"
    }
  ],
  "edition": "001"
}

Upload the folder to Pinata to ensure uniform URI lengths. Example URIs: ipfs://bafybeifhrrj3pvotihooenwljj4rreskvdb6dahxwq7cskpao73ishk2p4/000001.json ipfs://bafybeifhrrj3pvotihooenwljj4rreskvdb6dahxwq7cskpao73ishk2p4/000002.json ipfs://bafybeifhrrj3pvotihooenwljj4rreskvdb6dahxwq7cskpao73ishk2p4/000003.json

IPFS folder referance

Hook Installation

XRPLWin's dashboards simplify the process significantly. If you encounter issues, this is the go-to place. We'll install and set up the hook here.

Switch the connection to Xahau Testnet in the top-right corner of XRPLWin. Enter your testnet account seed or sign in with Xaman if deploying to mainnet.
Navigate to the tools section.
Focus on the Raw Transaction Sender and Install Hook from Hash. Use one of the following hook hashes:
- Testnet: 8F9F3EAC7945092D65F26D96BDC8E336F95F44BBFB381F18924E58A69DF62DD2
- Mainnet: 2D282A0F475B79510BE5B6CAEA2C655571A6B229BC36F8EB7B5E2650BE2EA93F
Click Install from Hook Hash, insert the appropriate hash, and proceed to the raw JSON transaction builder. The hook details will be pre-filled, as shown below:

XRPLWin's Install from Hook Hash

{
  "TransactionType": "SetHook",
  "Account": "YOUR_CONNECTED_rADDRESS",
  "Flags": 0,
  "Hooks": [
    {
      "Hook": {
        "HookHash": "8F9F3EAC7945092D65F26D96BDC8E336F95F44BBFB381F18924E58A69DF62DD2",
        "Flags": 1,
        "HookOn": "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF7FFFFFFFFFFFFFFFFFFBFFFFE",
        "HookNamespace": "4FF9961269BF7630D32E15276569C94470174A5DA79FA567C0F62251AA9A36B9"
      }
    }
  ]
}

Submit and sign the transaction to set the hook. Pay attention to the HookOn field, which defines the triggers (ttPAYMENT and ttINVOKE) for the hook.
Load the account with the URIs created earlier using Invoke transactions. The hook parameters are submitted as hex strings or uint64 integers. Use the Hex Visualizer to convert or validate inputs.

XRPL Hex Visualizer

Set the URI length (URIL :: 5552494C) to match the character length of your URI string. Use a string length tool to calculate. For example, the URI ipfs://bafybeifhrrj3pvotihooenwljj4rreskvdb6dahxwq7cskpao73ishk2p4/000001.json has 78 characters (78 :: 000000000000004E).
```
{
  "TransactionType": "Invoke",
  "Account": "YOUR_CONNECTED_rADDRESS",
  "HookParameters": [
    {
      "HookParameter": {
        "HookParameterName": "5552494C",
        "HookParameterValue": "000000000000004E"
      }
    }
  ]
}
```
Upload URI/NUM pairs for the hook to distribute. Each URI must be submitted individually via Invoke transactions. Convert the URI to hex using the Hex Visualizer and assign a NUM value (e.g., 1 :: 0000000000000001).

Invoke Raw JSON Example

Example:

URI: ipfs://bafybeifhrrj3pvotihooenwljj4rreskvdb6dahxwq7cskpao73ishk2p4/000001.json
URI Hex: 697066733A2F2F62616679626569666872726A3370766F7469686F6F656E776C6A6A34727265736B766462366461687877713763736B70616F37336973686B3270342F3030303030312E6A736F6E
NUM: 1
NUM Hex: 0000000000000001

{
  "TransactionType": "Invoke",
  "Account": "YOUR_CONNECTED_rADDRESS",
  "HookParameters": [
    {
      "HookParameter": {
        "HookParameterName": "555249",
        "HookParameterValue": "697066733A2F2F62616679626569666872726A3370766F7469686F6F656E776C6A6A34727265736B766462366461687877713763736B70616F37336973686B3270342F3030303030312E6A736F6E"
      }
    },
    {
      "HookParameter": {
        "HookParameterName": "4E554D",
        "HookParameterValue": "0000000000000001"
      }
    }
  ]
}

Repete this transaction changing the Value of each hook parameter with the following.

#2 URI HEX: 697066733A2F2F62616679626569666872726A3370766F7469686F6F656E776C6A6A34727265736B766462366461687877713763736B70616F37336973686B3270342F3030303030322E6A736F6E NUM HEX: 0000000000000002

#3 URI HEX: 697066733A2F2F62616679626569666872726A3370766F7469686F6F656E776C6A6A34727265736B766462366461687877713763736B70616F37336973686B3270342F3030303030332E6A736F6E NUM HEX: 0000000000000003

For each new URI, increment the NUM value (e.g., 2 :: 0000000000000002). Take care to convert each URI to hex accurately and verify using XRPLWin's dashboard to detect errors, delete namespaces, or monitor hook activity.

Testing and Debugging

Test Sucess

Test the hook by sending a payment from another testnet account to the hook account and observing the results. Monitor hook activity Here for testnet or Here for Mainnet

If you wanted to see the hook code or browse any other examples check out the Hook-101 Collection, this is example 017_InvokeUriRemit.c

XahauHooksNFTHandy_4ndyGetHooked