24-hour window
The 24-hour window is the period, defined by Meta, during which a business can reply freely to a user on the WhatsApp Business API without using templates. It opens every time the user sends a message and renews with each new message from them. Once the window expires, the business can only re-contact the person with a pre-approved template.
The mechanism protects users from spam: free-form conversation is allowed only when the customer has recently taken the initiative. Inside the window, the business can send any supported content (text, audio, images, documents, interactive messages) without prior approval. Every customer reply restarts the 24-hour count, so an active conversation can continue freely for days.
Extended windows exist for special cases: conversations originating from Click-to-WhatsApp ads or the Facebook Page button open a free 72-hour entry point, during which the business's messages are not billed. Service messages sent within the standard window are free; outside the window a template is required, billed according to the category and the recipient's country.
SendApp shows for each conversation whether the window is open or expired and, when needed, lets you send a template to reopen the contact, at Meta rates with no markups.
Frequently asked questions
From theory to practice
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