The same platform, explained for the job you are hiring it to do — by use case and by the kind of business you run.
Messages send from your own WhatsApp number, linked by scanning a QR code the way WhatsApp Web is linked. This is not the official WhatsApp Business API: there is no Meta approval queue and no template review, and in exchange the linked phone must stay online and only people who opted in should be messaged. See how it works.
Compare approaches in the API-alternative guide, or see pricing.