Add reminder calls to your own app with the ReminderIt API

Your own tools already know when things are going to happen. Your booking spreadsheet knows your appointments. Your home-automation setup knows when the bins go out. A little family app knows when Grandma's evening tablet is due. What those tools can't always do is make sure a person actually notices. Emails get filtered, push notifications get swiped away, and a dashboard only helps if someone looks at it.

A real phone call gets attention in a way other channels often don't. If you're building something where a missed moment has a real cost, adding reminder calls through an API can be one of the most useful things you wire up.

When reminder calls are worth adding

Reminder calls make the most sense when:

• Missing the event costs something: a wasted appointment slot, a missed dose, a late payment.
• The person isn't always looking at a screen: an older parent, a tradesperson, someone who works shifts or drives.
• Timing matters: the reminder is only useful if it lands at a specific moment.
• The event is already in your system: you already have the date and time.

Some examples:

• A booking tool that calls you, the owner, before each day's first appointment.
• A family app reminding a grandparent about their evening medication.
• A study planner that calls you before each exam slot.
• An internal tool ringing an on-call engineer at the start of a shift.
• A personal automation that turns your own scripts into calls.

Design decisions before you write code

A few questions are worth answering early, because they shape everything else.

Whose phone rings? Reminding yourself is simple. Reminding other people needs their consent. With ReminderIt, a person you want to remind has to accept once before your reminders reach them. Design your flow so they know this step exists. Each account can remind up to 5 people, so this suits personal, family and small-team tools rather than mass calling.

Which time zone? Store the person's time zone alongside their details, and schedule reminders in their local time, not your server's. A reminder for 9am in Chicago shouldn't be computed from a server clock in Europe.

When should it ring? The useful moment is usually before the event, when someone can still act: the evening before an early appointment, or 30 minutes before they need to leave.

What should it say? The call reads your reminder text aloud, so write it for the ear: short, specific, and without codes or abbreviations. "Your physio appointment is tomorrow at 10:15 at the Riverside clinic" beats "Appt #4471 tmrw 10:15".

What happens if they miss it? ReminderIt sends a WhatsApp message alongside the call and tries the call once more about five minutes later. Decide whether you also want to do something on your side.

A sensible build order

1. Read the reference. Start with the API reference at https://reminderit.com/developers/api to see what's available.
2. Create an API key. Log in at reminderit.com and go to Settings → Developers.
3. Keep the key secret. Store it as a server-side environment variable, never in a mobile app or front-end code.
4. Schedule a single reminder to yourself. A one-off, a few minutes from now. Check that your phone rings and the wording sounds right.
5. Add recurrence. Daily or weekly reminders, if your use case needs them.
6. Handle changes. When a booking moves or is cancelled in your system, update or cancel the reminder too. Stale reminders are worse than none.
7. Add other people. Once your own reminders work, add the consent step for anyone else.

If you use tools that can import an OpenAPI description, the spec is available at https://reminderit.com/openapi.yaml.

Mistakes to avoid

• Scheduling in the wrong time zone. The most common bug, and the most noticeable one when it causes a 3am call.
• Forgetting to cancel. Keep your system's record and the reminder in sync.
• Duplicate reminders. If your job runs twice, it shouldn't create two calls. Keep track of which bookings already have a reminder.
• Wording written for screens. Read your template out loud before you ship it.
• Calling without consent. Only remind people who've agreed to it.

Testing checklist

• Does a one-off reminder ring at the right local time?
• Does the text sound natural when read aloud?
• Does a cancelled booking also cancel the reminder?
• What happens around midnight, month ends and daylight-saving changes?
• Is your API key only on the server?

How ReminderIt fits

ReminderIt reminds you, and up to 5 people you choose, with a real phone call at the right time, in a warm, natural voice, plus a WhatsApp message with Done and Snooze buttons. It works in most countries, with 14 call languages, including English, Spanish, French, German, Hindi, Tamil and more.

Every plan includes 70 reminder calls a month and unlimited WhatsApp reminders. If you need more, you can add extra calls anytime, for example 25 extra calls for $5. Plans are $7 a month, $59 a year, or $99 once for two years, and there's a 7-day free trial with no card needed.

If you don't want to write code at all, you can also connect Claude or ChatGPT and ask them to set reminders, or just set them yourself on WhatsApp.

Building something and want to talk it through? Message us on WhatsApp and tell us what you're making.