Definition
The Messenger Platform is Meta's set of APIs and webhooks that lets businesses send and receive messages with people through their Facebook Page on Messenger, and through Instagram professional accounts, from their own software.
Businesses connect a Facebook Page, receive incoming messages through webhooks and reply with the Send API. Conversations must be started by the person. A business cannot cold-message users on Messenger.
Meta's documentation defines a 24-hour standard messaging window. It opens when a person messages the Page, clicks a Click-to-Messenger ad and sends a message, or comments on a post. Within it, the business may send promotional and non-promotional messages.
Outside the window, messages need a message tag that matches an allowed use case. The Human Agent tag lets a person on the business's team reply manually within 7 days. Meta's documentation warns that from 27 April 2026, requests using the CONFIRMED_EVENT_UPDATE, ACCOUNT_UPDATE and POST_PURCHASE_UPDATE tags return an error, so do not build on them.
Messenger is useful as one channel in a shared inbox alongside WhatsApp, Instagram and SMS. Plan around the 24-hour rule: route Messenger conversations to agents quickly, and use the Human Agent tag only for genuine human follow-ups.