An experiment — watch this page

This page is already fading from your memory.

Within an hour, about half of what you read today will be gone. Within a week, most of it. Not because you didn't pay attention — because nothing reminded you at the moment it started to slip. Watch: it's happening to this very paragraph.

Start studying free See the science

✓ No credit card. Kioku does what that Review button does — for every card, on schedule, forever.

The fix is small

Thirty seconds, at the right moment.

That's all a review is. Kioku turns your notes, PDFs, lectures, and links into flashcards — then uses the FSRS-5 algorithm to surface each one right before it slips. Try the loop; the intervals under the buttons are the schedule deciding in real time.

Finance · 1 of 4🔥 6-day streak
Question
Opportunity cost
tap to reveal the answer
Answer
The value of the next-best alternative you give up when you make a choice.
how well did you know it?
✓

Session complete

4 cards reviewed · +32 XP · the schedule takes it from here

Grade honestly — that's what teaches the scheduler your memory.
The science

Your brain forgets on a curve. Kioku schedules against it.

  • 1Without review, memory decays fast — most of a lecture is gone within days. That's the dashed line.
  • 2Each quick review resets the curve and flattens it. The next one can wait longer: a day, then four, then weeks.
  • 3Kioku times every card for you with FSRS-5, so you only ever see what you're about to forget. Knowing the curve is its job, not yours.
Memory Time → +1d +4d +12d
Reviewed with Kioku Read once, never reviewed

Reviewed on time, it stops fading.

Everything below is how Kioku makes that automatic.

What Kioku does

The cards make themselves. You just show up.

Making good flashcards used to be the homework before the homework. Kioku builds them from whatever you already have.

Type a topic, get a deck

Describe what you're studying — or paste notes, or drop a PDF — and the AI writes clean, atomic cards. Q&A, cloze deletion, or reverse. Every card editable before you save.

Make me 20 cards on key macro terms
Crowding out

When government borrowing raises rates and reduces private investment.

Record the lecture

Hit record in class. Kioku captures the audio, transcribes it accurately — including on iPhone — and turns the transcript into a study guide or a ready deck.

Recording · 12:47
"…the mitochondria is the site of oxidative phosphorylation, where the electron transport chain…"
📝 Study guide🃏 Flashcards

Sit a real mock exam

SAT, AP, MCAT, or your finals — timed, with difficulty that adapts to your accuracy and speed, a predicted score on the real scale, and an AI explanation for every miss.

Which lever is monetary policy?
Raising income tax rates
Lowering the federal funds rate ✓
Increasing public spending
Predicted score · 512

Also in the box

✓Import from a link — YouTube or any article becomes cards, a quiz, and a summary.
✓Photo & PDF import — OCR your handwritten notes; long docs are chunked automatically.
✓CSV import — bring existing decks straight in from a file.
✓Audio on cards — attach or record real pronunciation; natural TTS with language detection.
✓LaTeX math — formulas render beautifully; images and hints too.
✓Tap-to-define — tap any word mid-review for an instant AI definition.
✓Share by code — any deck becomes one compact code a friend can paste.
✓Stats that matter — a year heatmap, review forecast, hardest cards, weakest topics.
✓Streaks & XP — daily goals, 70+ achievements, streak freezes, cloud sync everywhere.
How it works

Three steps, spaced like your reviews.

day 0

Make a deck

Type a topic, paste notes, upload a PDF, record a lecture, or paste a link. The AI drafts the cards; you approve them.

day 1

Review for minutes

Flip, grade, done. Type-the-answer and quiz modes keep recall active; the grades teach the scheduler your memory.

day 5 →

Watch it hold

Cards you know drift out to weeks and months; shaky ones come back sooner. Your dashboard shows retention climbing.

Stuck on a card?

There's a tutor in the margin.

Every card has help on call. Ask for an example, a breakdown, an analogy, or a memory hook — without leaving your review. Try one:

The card
Compound interest
Interest earned on both the principal and previously accrued interest.
Need a hand?
記Kioku tutor
The difference

Cramming rents knowledge. Spacing owns it.

The night-before method

  • Re-read and highlight, hope it sticks
  • Cram everything the night before
  • Spend hours making cards by hand
  • Review what you already know anyway
  • Find your weak spots during the exam

The Kioku method

  • Active recall on every card — proven to stick
  • Spaced so it lands in long-term memory
  • AI drafts the deck in seconds from your material
  • Only see cards you're about to forget
  • Dashboard shows weak spots before the exam does
Pricing

Start free. Stay free.

Make an account and study today — no card required.

Free
$0 /forever

Everything you need to actually learn.

  • Unlimited decks & cards
  • FSRS-5 spaced repetition
  • AI generation, lecture & link import
  • PDF / image / text / CSV import
  • Adaptive exam simulator & stats
  • Deck sharing & cloud sync
Get started free
early access
−80% off!
Pro
$25$4.99 /month

For heavy AI users — lock in the launch price.

  • Everything in Free
  • Much higher daily AI allowance
  • Priority generation
  • Unlimited PDF & image imports
  • Early access to new features
Get Pro for $4.99
FAQ

Questions?

Everything you might want to know before you start.

Is Kioku free to use? +
Yes. Create a free account and you get unlimited decks, spaced repetition, exam mode, and cloud sync — with a fair daily AI allowance. Pro ($4.99/mo during early access, normally $25) raises the AI limits for heavy users.
Do I need an account? +
Yes — Kioku saves your decks, streaks, and progress to your account so they sync across every device. Signing up takes a few seconds with Google, GitHub, or email.
Do I need to know anything about spaced repetition? +
Not at all. Kioku handles the scheduling for you using the FSRS-5 algorithm. You just study the cards it shows you each day — the timing is automatic.
Where do my cards come from? +
However you like: describe a topic and let the AI build a deck, paste your own notes, upload a PDF or photo, record a lecture, paste a YouTube/website link, or import a CSV of existing cards. You can always edit anything before saving, or write cards by hand.
Can it really transcribe a lecture? +
Yes. The lecture recorder captures your class and transcribes it for you, then turns the transcript into a study guide or a deck. Because the audio is transcribed on our servers, it works on any modern browser — including Safari on iPhone.
What can the exam simulator do? +
Pick the SAT, an AP exam, the MCAT, or your finals and Kioku generates a timed mock exam. Difficulty adapts to your accuracy and speed, you get a predicted score on the real scale, a per-topic breakdown, and an AI explanation for every question you miss.
Can I share decks with friends? +
Yes — any deck becomes a single compact code. Send it to a friend, they paste it in, and the whole deck (cards and tags included) is added to their collection instantly.
Will my decks sync across devices? +
Yes. When you sign in, your decks, stats, and progress save to your account and follow you to any device you log in on.
What subjects does it work for? +
Anything you'd use flashcards for — languages (with audio and cloze deletions), STEM (with LaTeX math rendering), vocabulary, history, professional exams, and more.
Can I study on my phone? +
Yes — Kioku is built for touch. Tap to flip, swipe to grade, and it works right in your mobile browser. No app store required.
Last card

Will you remember this page tomorrow?

tap to reveal the answer

Answer

Only if you review it.

Your first deck takes 60 seconds — and it's free.

Start studying free no credit card · syncs everywhere
Memory of this page
100%
decaying while you read…