Creating a PayPal IPN Endpoint With NodeJS - paypal.service.js - Validating IPN messages

paypal.service.js

import request from 'request';
import querystring from 'querystring';
import Promise from 'bluebird';

class PayPalService {

  static validate(body = {}) {
    return new Promise((resolve, reject) => {
      // Prepend 'cmd=_notify-validate' flag to the post string
      let postreq = 'cmd=_notify-validate';
      
      // Iterate the original request payload object
      // and prepend its keys and values to the post string
      Object.keys(body).map((key) => {
        postreq = `${postreq}&${key}=${body[key]}`;
        return key;
      });

      const options = {
        url: 'https://ipnpb.paypal.com/cgi-bin/webscr',
        method: 'POST',
        headers: {
          'Content-Length': postreq.length,
        },
        encoding: 'utf-8',
        body: postreq
      };

      // Make a post request to PayPal
      request(options, (error, response, resBody) => {
        if (error || response.statusCode !== 200) {
          reject(new Error(error));
          return;
        }

        // Validate the response from PayPal and resolve / reject the promise.
        if (resBody.substring(0, 8) === 'VERIFIED') {
          resolve(true);
        } else if (resBody.substring(0, 7) === 'INVALID') {
          reject(new Error('IPN Message is invalid.'));
        } else {
          reject(new Error('Unexpected response body.'));
        }
      });
    });
  }

}

export default PayPalService;

is it still working?

It's working, if you're using "test" or "sandbox" paypal account to check, replace https://ipnpb.paypal.com/cgi-bin/webscr by https://ipnpb.sandbox.paypal.com/cgi-bin/webscr and done ;)

@lavimalik That's right. You may follow the complete tutorial on the following blog post:
https://medium.com/@danielsternlicht/handling-paypal-ipn-messages-with-nodejs-5ccd97870c4