Fun fact of the day app: the one that tells you why

By the edgi team Updated October 28, 2026

The best fun fact of the day app is edgi. It gives you a strange fact, plays it with you as a 60-second Lesson so you know why it's true, and keeps it as a card on a Map of everything you've learned, so tomorrow's fact lands next to today's.

We make edgi, and we built it for people who read a great fact and immediately want to know how.

Prices are from each app's US App Store listing, checked October 28, 2026.

Today's fun fact

A dolphin is closer kin to a hippo than to a shark.

A fact app hands you that sentence, at best with a source. edgi hands you the minute after it. You guess which two of the three are related, then find out why fast swimming gave a mammal and a fish the same torpedo shape, and what in the tail and flipper bones gives the dolphin away:

Convergent Evolution Convergent evolution is the independent development of similar traits in species from completely different evolutionary branches.

60-second Lesson

Convergent Evolution

A dolphin is closer kin to a hippo than to a shark. Guess first, then see why they look alike.

Play it here Read about convergent evolution

Finish it and convergent evolution is your card. Tomorrow's fact could sit right next to it on the Map: a shark can feel the electric field of a fish buried in sand, and life has invented its own light at least 94 separate times. Each one you play lights up beside the last.

Why a fact of the day fades

A fact with nothing to hang it on is mostly gone by the next day. That's what Hermann Ebbinghaus measured in the 1880s, for lists of nonsense syllables rather than facts, and a 2015 replication in PLOS ONE (Murre and Dros) got results "similar to Ebbinghaus' original data," with most of the loss in the first day. A Lesson makes you guess and check before it tells you anything, so the fact arrives as an answer to a question you just asked. The curve itself is a Lesson too: the forgetting curve.

The other fact apps

Factful is the careful one: one fact a day on your lock screen, each with a "Why it's true" page that cites its source, and its site promises "no streaks to keep." It's new and has no App Store ratings yet. Premium is $1.99 a week, $4.99 a month or $29.99 a year, and "Factful+" is $79.99.

Facts by Monkey Taps is the big one: 4.77 stars from 69,150 App Store ratings, on iPhone and Android, with thousands of facts and riddles. The free version has ads; Premium removes them and adds saving and search, across nine paid items from $4.99 to $139.99.

Fact of the Day by Zaffles is the simplest: one fact with a picture each day, a widget, and it works offline. 4.81 stars from 316 ratings. Its only purchase is a $1.99 "Lifetime Supporter" item.

Fun Fact of the Day by Daru adds 10-day themed collections, a streak and a widget. Paid items: $3.99 to remove ads, $8.99 to unlock all facts, Premium at $14.99 a year or $24.99.

If you'd rather pull facts whenever you want one, see apps to learn random facts.

Pick something else only if…

• You only want the sentence on your lock screen, nothing to tap: Fact of the Day.
• You want every fact with a citation link: Factful.
• You need Android: Facts by Monkey Taps.

FAQ

What's the best fun fact of the day app? edgi, if you want to know why the fact is true and keep it. Factful if you want one sourced fact on your lock screen.

Is there a free fun fact of the day app? Yes. edgi is free, and Factful, Facts, Fact of the Day and Fun Fact of the Day are all free to download, with paid extras.

Which fun fact app has a widget? Fact of the Day, Fun Fact of the Day and Factful all list widgets.

Are the facts in fact apps true? Factful cites a source for every fact, and edgi's Lessons show you the reasoning so you can check it yourself. The other listings on this page don't mention sources.

Is edgi free? Yes. edgi is free: Lessons, cards, Sets and the Map.