Add SMS Reminders to a Base44 App With Twilio

To add SMS reminders to a Base44 app with Twilio, you do four things: get a Twilio number and finish its registration, store the Twilio credentials as secrets in your app, ask your AI builder for one backend function that sends a text, and run that function on a schedule (for example, 24 hours before an appointment). Build it for one reminder first, test it with your own phone, then widen it.

This guide is for non-technical founders. You won't write the code yourself, but you need to know what to ask for, what to check, and which rules apply before a single customer gets a text.

When SMS reminders are worth it

Text messages get seen quickly, which makes them useful for things with a time attached: appointments, deliveries, renewals, class sessions. They are a poor fit for anything long or promotional. If a reminder needs more than a couple of sentences, send an email and link to it.

Before you build: consent and registration

This is the part most tutorials skip, and it is the part that can get your number blocked.

• Get permission first. Only text people who agreed to receive texts from you, and say what the texts are for when they sign up. Add a checkbox to your booking or signup form; don't pre-tick it.
• Offer a way out. Every message flow should honor "STOP". Twilio handles standard opt-out keywords on its numbers, but your app must not keep texting someone who opted out.
• Register your number. In the US, business texts to US phone numbers generally require registration (Twilio calls it A2P 10DLC). Rules differ by country and change over time, so read Twilio's current guidance before you launch. Registration can take days, so start it early.

This is not legal advice. If you text people in several countries, check each country's rules.

What you need

1. A Twilio account with a phone number that can send SMS.
2. Your Account SID, Auth Token and sending number. Treat the token like a password.
3. A place in your app that stores each person's phone number and their text consent, plus the date and time of the thing you are reminding them about.

Step 1: Store the credentials as secrets

In your Base44 app's settings, add secrets for the Twilio Account SID, the Auth Token and the sending number. When you prompt the AI builder, refer to them by name. Never paste them into the chat. If you did, rotate the token in Twilio.

Step 2: Ask for one small backend function

Sending has to happen on the backend, where the credentials stay hidden. A prompt like this keeps the AI in bounds:

Create a backend function called sendReminderSms that sends a text through Twilio using the secrets TWILIO_ACCOUNT_SID, TWILIO_AUTH_TOKEN and TWILIO_FROM_NUMBER. It takes a phone number and a message. Only send if the contact has sms_consent = true. Do not change any other function, page or data structure. Never display the secrets.

The consent line matters. Without it, a bug can text someone who never agreed.

Step 3: Test with your own phone

Create a test booking with your own number and trigger the function. Check:

• Did the text arrive, from the right number?
• Is the message short, with your business name in it?
• Does Twilio's message log show it as delivered?
• Does a contact with consent turned off get nothing?

Step 4: Send it on a schedule

A reminder needs something to trigger it. Ask your AI builder for a scheduled function that runs, say, every hour, finds bookings starting in about 24 hours that haven't been reminded yet, sends the text, and marks each one as reminded. That last flag is what stops duplicates.

A good reminder is plain and useful:

Hi Sam, a reminder from Kode Studio: your session is tomorrow at 2:00 PM. Reply STOP to opt out.

Common problems

• Nothing sends: a secret name in the function doesn't match the one in settings, or the number isn't registered yet.
• Texts are blocked or filtered: registration isn't finished, or the message looks like spam. Keep reminders short and specific.
• People get the same text twice: the "already reminded" flag is missing.
• Wrong time: your app and your customers are in different time zones. Store the time zone with the booking.

Where a prompt pack helps

If you'd rather not write each prompt from scratch, the Twilio SMS Marketing System is a set of build prompts for adding SMS to a Base44 app. It is a downloadable resource, not hosted software: you still create your own Twilio account, follow Twilio's rules, and test everything yourself.

If you already send email from your app, the same pattern applies: Send Emails From a Base44 App With Resend walks through it. And before you add any new feature, back up your app first.

Key takeaways

• Get consent and finish number registration before you text anyone.
• Keep Twilio credentials in secrets, never in the chat or a page.
• Ask for one backend function, test with your own phone, then add the schedule.
• Track an "already reminded" flag so nobody gets duplicates.

FAQ

Do I need to know how to code? No, but you need to check the results: delivery, consent handling and timing.

Can I use SMS for promotions too? Promotional texts have stricter consent rules than reminders. Check Twilio's guidance and your local rules before sending any.

What does it cost? Twilio charges per message and for the number; see Twilio's pricing page for current rates.