If you are looking at anything built on WhatsApp for business use, there is one rule you need to understand before you evaluate features, because it shapes what any such tool can and cannot do.
The rule
Meta lets a business send free-form messages to somebody only within 24 hours of that person messaging the business. Inside that window you can write whatever you like, as many times as you like. Outside it, you may only send a message built from a template Meta approved in advance.
The window reopens every time the person writes to you, and it is per person – not per business. So on a team of ten, some people will be inside the window and some outside it at any given moment.
The reason for the rule is obvious once stated: without it, WhatsApp would be a marketing channel within a month, and it would be worthless to everybody. The rule is what keeps your team’s inbox usable.
What it means in practice
For a team assistant, the consequences are specific.
Replies are free-form and free. A staff member sends their daily plan; the assistant answers immediately, in whatever words suit. No template, no fee. This covers the overwhelming majority of messages.
Reminders often are not. If somebody last wrote yesterday morning and their job is now overdue, they are outside the window. That reminder has to go as an approved template, and it carries Meta’s fee.
Templates are approved in advance, not written on the fly. A template is a fixed sentence with slots – “Reminder: {{1}} is due {{2}}” – submitted to Meta and approved, usually within a day or two. You cannot improvise one at send time.
Somebody has to track the window per person. This is the part that has to be built properly. A tool that does not track it will simply fail to send, silently, and the owner will never find out that half the reminders never went.
What it costs
Free-form replies inside the window cost nothing. Template messages sent outside it are charged by Meta at a per-message rate that varies by country – typically well under a cent in most markets, and Meta publishes the current rates. For a ten-person team it is usually a few dollars a month.
The important thing is who pays it. In a properly self-hosted setup, that fee goes from your own WhatsApp Business account to Meta, at Meta’s rate, with no margin added. Ask any vendor whether the message fees are billed to you at cost or through them – the answer tells you something about the pricing model.
What this rules out
The window is also why you should be sceptical of anything that seems to sidestep it.
Tools built on unofficial libraries – whatsapp-web.js, Baileys and similar – drive WhatsApp Web as though a person were typing, so they are not subject to templates or fees at all. That sounds like an advantage until you consider that it puts your business number outside the interface Meta supports, and Meta acts against unofficial automation. If the number your whole team relies on is suspended, no feature compensates for it.
So the question to ask any vendor is short: is this the official WhatsApp Business Cloud API? The answer is one word, and the follow-up – “how do you handle the 24-hour window?” – tells you whether they have built it properly or discovered it late.
How we handle it
Bosun uses Meta’s official Cloud API. It tracks each person’s window and chooses automatically: a free-form reply inside it, an approved template outside it. Two templates are set up during installation – one for overdue reminders, one for the end-of-day nudge – and approved before you go live, so reminders work from the first day rather than failing quietly.
You never see a failed send, and you never have to think about which kind of message is going. More on the channel in the WhatsApp assistant, and on what the reminders actually do in automatic follow-up.