Learn a fact in 4 seconds
WONDER feeds you one fascinating fact at a time and makes sure it sticks with spaced repetition. Five minutes a day. Forever curious.
20 facts free every day · no email required to browse
How it works
Read
Swipe through a feed of short, verified facts. 4 seconds each. No doomscrolling, just wonder.
Remember
Facts you like become flashcards. FSRS spaced repetition schedules them right before you'd forget.
Grow
Build your streak, earn XP, watch your knowledge graph bloom. Bragging rights included.
Why WONDER
4-second facts
Attention span-friendly. Optimized for the busiest schedules.
FSRS memory engine
State-of-the-art spaced repetition. Reviews right on time, every time.
Curated packs
Hand-picked fact collections — space, history, psychology and more.
Offline 100%
PWA with offline support. Learn on the train, plane, anywhere.
Anki export
Take your deck with you. Export cards to Anki (Pro).
Multi-language
English facts today, more languages on the way.
150k+
facts in the vault
4s
per fact
90%
retention target
0
need for prior knowledge
FAQ
Is WONDER really free?
Yes — 20 facts a day, forever, on the Free plan. Upgrade to Pro for unlimited facts, search and Anki export.
Where do the facts come from?
Open corpora: Wikipedia Did You Know, science-facts archives and curated feeds. Every fact links to its source. See licenses.
How does spaced repetition work?
We use FSRS-5, the same algorithm powering modern flashcard apps. The perfect moment to review a fact is right before you would forget it — FSRS computes that.
Can I use WONDER offline?
Yes. WONDER is a PWA — install it and your review queue works without an internet connection.