JavaScript Library for W-9 and W-8BEN

This JavaScript library helps you collect, generate, and keep track of commonly requested IRS forms such as W-9, W-8BEN, and W-8BEN-E using the Nextform API.

Install

npm i @balancer-team/nextform

Usage

Provide your API key and optional webhook secret to the Nextform constructor. You can obtain a free API key by signing up at nextform.app.

import { Nextform } from '@balancer-team/nextform'

const nextform = new Nextform({
  apiKey: 'YOUR_API_KEY',
  webhookSecret: 'YOUR_WEBHOOK_SECRET',
})

Set up a session by calling createSession with the desired form type. The form type can be one of the following:

• w9 - Form W-9 (Request for Taxpayer Identification Number and Certification)
• w8ben - Form W-8BEN (Certificate of Foreign Status of Beneficial Owner)
• w8bene - Form W-8BEN-E (Certificate of Status of Beneficial Owner for Entities)

const session = await nextform.createSession({
  formType: 'w9', // or 'w8ben' or 'w8bene'
})

// Output:
//
// {
//   id: 'oymuG8Hz2NJJVrEvYNM5e',
//   formType: 'w9',
//   reference: '',
//   status: 'open',
//   url: 'https://nextform.app/form/w9/oymuG8Hz2NJJVrEvYNM5e',
//   ...
// }

The session object contains a URL that you can use to open the form in a browser. Redirect your users to this URL to collect the form data.

Receive and Verify Webhooks

To receive webhooks, set up a webhook endpoint in your application. The endpoint should verify the webhook signature using the verifyWebhook method. This ensures that the webhook is from Nextform and not from an unauthorized source. The below example uses the express library to set up a simple webhook endpoint. Modify the code below to use your preferred web framework.

router.post('/webhook', async (req, res) => {
  // Obtain the signature and body from the request
  const signature = req.get('Nextform-Signature')
  const body = JSON.stringify(req.body) // Assumes you are using express.json() middleware

  // Verify the webhook signature
  const isVerified = nextform.verifyWebhook({ signature: signature, body: body }) // true or false
  if (!isVerified) return res.status(401).send('Invalid signature.')

  // Add your code to handle the data from the webhook
  const data = req.body
  // ...
})