Advanced

Custom integrations

As of now, World ID only includes a for use in web projects. However, creating a custom integration to use World ID in other type of projects (e.g. mobile apps) is fairly straightforward. Below you will find details on how to do this.

Overview

Creating a custom integration involves the following process:

On the frontend side:

  1. Establishing a connection to the Worldcoin app through .
  2. Sending a wld_worldIDVerification JSON-RPC 2.0 request with the required proof input.
  3. Receiving the proof results through WalletConnect.
  4. Handling errors received from the Worldcoin app appropriately.

On the blockchain side:

  1. Deploy your own smart contract that validates the ZKP and executes whatever action you want.
  2. Submit a regular ETH wallet transaction containing the ZKP params.

Details

Tip

1. Connecting to the Worldcoin app

Follow the to connect your app to the Worldcoin app. We strongly recommend you use the same UI/UX patterns used in the JS package.

Screenshot for World ID modal

Example:

import WalletConnect from '@walletconnect/client'
import { buildQRData } from '@worldcoin/id'

// Create a connector
const connector = new WalletConnect({
  bridge: 'https://bridge.walletconnect.org',
})

const url = buildQRData(connector) // Of course alternatively, you can simply copy this code from the JS widget

Caution

2. Send verification request

The Worldcoin app will automatically accept the connection request after the user scans the QR code with their app. Upon the connection being established, send the verification request as a JSON-RPC 2.0 message with the following structure.

const request = {
  id: 1000, // use a different ID every time
  jsonrpc: '2.0', // always `2.0`
  method: 'wld_worldIDVerification', // always `wld_worldIDVerification`
  params: [
    {
      signal: '0x4976fb03c32e5b8cfe2b6ccb31c09ba78ebaba41', // example; enter relevant signal here (e.g. user's wallet address)
      action_id: 'wid_BPZsRJANxct2cZxVRyh80SFG', // example; use the action ID from the Developer Portal
    },
  ],
}

Example (partial, see #4 for complete snippet):

await connector.sendCustomRequest(request)

3. Receive the proof

When the Worldcoin app receives the verification request, it'll show a prompt to the user to confirm they want to verify their request. Once the user approves this request, you will receive the proof results. The proof result will be a JSON object with 3 ABI-encoded string parameters, which your smart contract should expect (note that when submitting to a smart contract, you should include the entire proof array of 8 BigInts, i.e. uint[8]). Read more about the received response .

Example (partial, see #4 for complete snippet):

const { merkle_root, nullifier_hash, proof } =
  await connector.sendCustomRequest(request)

4. Handle errors appropriately

You should properly handle errors when interacting with the Worldcoin app. There are some error cases that in particular should be expected. For example, if the user declines the verification request in the Worldcoin app. Check out the list of for details on possible error codes.

Example:

try {
  const { merkle_root, nullifier_hash, proof } =
    await connector.sendCustomRequest(request)
} catch (errorResult) {
  const { code, detail } = errorResult
}

5. Blockchain integration

Upon completing the integration steps above the only thing that remains is integrating the blockchain side. This process is the same as if you were using the . We recommend you check out Step 4 and onwards from the guide.