The two tools people mix up
Ask about text reminders and you get two completely different products in the same answer. The first is a booking system that knows each client's appointment and texts them individually about it. The second is a broadcast tool that sends one message to everybody.
If you need each client reminded about their own slot, you need the first kind. That means a booking system with reminders built in, and it means a monthly fee. There is no way around this, and any service claiming to do it for a dollar is not doing what you think.
If you need to reach your entire client list at once with the same message, the second kind is far cheaper and far simpler. Most businesses eventually use both.
What a broadcast is genuinely good at
The clearest use is anything unplanned. The power is out, the road is closed, you are ill, the practice is shutting early. Every client needs the same sentence and they need it now, not in the reminder queue for tomorrow.
The second use is filling gaps. A late cancellation leaves a hole at 3pm on Thursday, and one message to your list asking who wants it will usually fill it faster than phoning down a waiting list.
The third is seasonal. Booking pushes before holidays, a new service, a price change, or the annual reminder that it has been six months since most people came in. One message, whole list, one payment.
What it honestly cannot do
It cannot personalise. Everyone on the list gets the same words at the same time, so there is no client name and no individual appointment time in the message.
It cannot read your calendar. Nothing syncs with your booking software, so nobody is reminded automatically when they book.
And messages go at 12pm Eastern on the date you choose rather than at an arbitrary hour, which matters if you wanted a reminder at 6pm the night before. If any of those three things is essential to you, a booking system is the right purchase and this is not.
What each option costs
Booking systems with reminders built in typically start somewhere around twenty to forty dollars a month depending on the provider and how many staff you have. That is a fair price for what it does, and it is a recurring cost whether you are busy or quiet.
A broadcast is priced per event instead. Five dollars covers one message to up to 100 clients and nineteen covers up to 500. Each later message is charged the same way.
For a business that is quiet in January and flat out in December, paying only when you send is a real advantage. Leaving a subscription you barely use covers that trade in more detail.
Getting a client list built
Clients add themselves through a sign-up link or a QR code, which is what keeps the whole thing permission-based. You are not uploading a contact list you gathered from booking forms, and you are not guessing whether someone agreed to be texted.
In practice a QR code at the front desk and the link in your email signature will build a list surprisingly quickly, because clients who are already loyal will sign up without being chased.
Once the list exists you can keep sending to it. Sending promotions and announcements to a customer list covers what to send once you have one, and the rules on opt-outs covers the compliance side.