What is the best countdown app?

The best countdown app is the one that keeps your dates in view without being opened: widgets, Lock Screen counts and a calendar view, from a developer who will still be maintaining it when your date finally arrives. Event Countdown has counted down since 2015 and is rated 4.7 from over 132,000 ratings on the App Store and Google Play.

What to look for in a countdown app

Whichever app you choose, these are the things that separate a keeper from a delete-after-the-wedding download:

Countdowns where you look, not just inside the app: Home Screen widgets, Lock Screen widgets, and on newer iPhones a Live Activity or Dynamic Island countdown for the final hours.
A calendar view as well as a list, so a busy month reads at a glance.
Alerts you control, so the date never arrives unannounced.
Sharing, for the countdowns that belong to more than one person.
An honest free tier, so you can live with the app before paying anything.
A track record. Countdowns are long-lived by nature; an app abandoned next year is no use for a wedding the year after.

How Event Countdown measures up

Counting down since 2015, with 5.9 million downloads and over a million people using it every month.
Rated 4.7 from more than 132,000 ratings.
The full widget collection: five widget types including a live ticking countdown, plus Live Activities and the Dynamic Island.
Calendar View: a countdown calendar of your own events.
Share countdowns that stay in step on everyone's phone, or turn one into a video for the group chat.
Free with unlimited countdowns and no account; Premium is there when you want more.

The honest answer is that "best" depends on what you count down to. If you want one date on a pretty screen, plenty of apps manage that. If you want every date that matters, visible everywhere, from an app that will still be here next year, that is what Event Countdown was built for.