You studied it.
Now keep it.

Here's a week most students know. You study a new Physics topic on Monday, a Chemistry chapter on Tuesday, some Maths on Wednesday. It all makes sense while you're reading it.

Then you say: "I'll revise everything on Sunday."

Sunday comes, and three things go wrong:

• Monday's topic is already mostly gone. You aren't revising it. You're learning it again from scratch.
• One day isn't enough. Six days of new material won't fit into one evening, so some topics get skipped.
• Next Sunday it's worse. Now there are two weeks of topics, then three. The old ones quietly drop off the list and never come back.

Revision isn't a one-day event. It's a cycle you repeat for every topic, at gaps that are worked out for that topic. Doing that by hand for hundreds of topics is impossible. That's the job Re:Call does for you.

In 1885 a German scientist, Hermann Ebbinghaus, tested his own memory for months and found the forgetting curve: you lose most of a new memory in the first days, then the rest fades more slowly.

He also found the cure. Every time you successfully revise something, the curve gets flatter, so you can wait longer before the next revision. This is called spaced repetition, and it's one of the most tested ideas in learning science.

The trick is timing. Revise too early and you waste time on something you still know. Too late and it's already gone. The sweet spot is just before you'd forget.

Look at the numbers. Sunday revision and Re:Call use about the same number of revisions. The difference is when they happen. Re:Call revises a topic while you still mostly remember it, so each revision makes the memory stronger instead of rebuilding it from zero.

One more finding that matters for exams

A 2008 study by Cepeda and colleagues (over 1,350 people) found that the best gap between revisions depends on how far away the test is: roughly 20–40% of the time left when the test is a week away, and 10–20% when it's months away. So as your exam gets closer, gaps should get shorter. Re:Call does exactly this when you add your exams (Level 60).

Three things make Re:Call different from a flashcard app:

• It only reminds you. There are no flashcards to make and no notes to type. You revise from your own book, notes or PDFs. Re:Call just tells you which pages and when.
• It knows your exam dates. Normal spaced-repetition apps keep stretching gaps to months. Re:Call squeezes them to fit before each exam, then gives every topic a final revision right before it. SAT in December, boards in February? Add both.
• Everything stays on your computer. No account, no sign-up, no internet needed, no cloud.

The six screens

Everything lives in the sidebar on the left. Jump to any screen with ⌘1–⌘6 on Mac or Ctrl+1–Ctrl+6 on Windows.

☀️ Morning: open your to-do list

When your quiet hours end (7 am by default), a notification arrives: "📚 Today: 6 revisions — Physics Ch 4, Chem Ch 2, …". Each row on Today shows the topic, subject, chapter, and the exact range to revise (like "Faraday's law → AC generator"). Each row has two buttons:

• ✓ (tick): I revised it. Re:Call asks how well you remembered.
• ✗ (cross): Not today. The topic moves to tomorrow.

Rows you finish stay on the list (ticked or crossed), so you can see your progress through the day. Topics also send their own reminder at the moment they're due, like "Revise: Physics · Ch 4 · Current Electricity (Page 45 → 62)".

How to rate (be honest, it's only for you)

Pressed the wrong one? An Undo bar shows for 8 seconds after every ✓ or ✗. You can also press U on Today, or ⌥⌘Z / Ctrl+Alt+Z anywhere.

📖 After studying: add the topic

Click + Add Topic (or ⌘N / Ctrl+N) and fill in:

Tip: make topics bite-sized. "Wave Optics, Huygens to YDSE" works better than "All of Optics". Small topics are quicker to revise and easier to rate honestly.

🌙 Night: log your study time

The "How much did you study?" card at the top of Today asks for your hours and minutes. You type it yourself; the app never guesses. If you forget, a reminder comes at 9 pm. You also have until the end of tomorrow to fill it in (see Level 50).

⌨️ Do it all from the keyboard

On Today you never need the mouse:

Holding a key never repeats it, so holding X can't accidentally skip your whole list.

🔁 Trouble topics

If you forget a topic 4 or more times, revising clearly isn't working. Re:Call flags it as a trouble topic and shows a pink card on Today.

Skipping the same topic 3 times in a row also turns it red, as a gentle "you keep avoiding this".

Re:Call is relaxed about almost everything, except this. It's how the app keeps you honest with yourself, and it's what makes the Stats grid meaningful.

1. You get two days to fill each day. Monday's time can be typed or edited any time on Monday or Tuesday.
2. After that it's locked forever. On Wednesday, Monday's number can't be changed.
3. If a day is left empty past its window, the app locks. You can't add topics or log other days until you fill the missed day. You fill missed days in order, oldest first.
4. 0 is a valid answer. Had a day off? Type 0 h 0 m. The app only wants the truth.

In Settings → "How much can you study?" there's a five-step slider. Each step sets a target recall: the chance you'll still remember a topic when its revision comes up. Higher target = shorter gaps = more revisions per day. 💪 Focused is the default and suits most exam prep.

What exam mode does

Add your exams in Settings → Exams (or right on the Stats screen). Give each one a name and a date, and pick the subjects it covers, or leave it on All subjects. Each topic prepares for the next exam that covers its subject; once that exam is over, it moves on to the next one. So with the SAT (Maths, English) on 6 Dec and boards (all subjects) in February, Maths topics squeeze in before the SAT while Physics spreads out until the boards. From then on, for each topic:

• Gap cap: no gap can be longer than a share of the days left (40% on Focused). With 100 days left, no gap is over 40 days. With 10 days left, no gap is over 4. That's the Cepeda finding from Level 10.
• Final sweep: every topic gets one last revision in the final days before the exam (7 days on Focused). Your weakest topics come first.
• Daily limit: if too many revisions land on one day (over 40 on Focused), the ones you know best move to nearby days.
• Never past the exam: no revision, not even a skipped one, gets pushed beyond your exam or out of the final sweep.
• Re-planned every morning against the days left.
• After the exam, the caps switch off and Re:Call goes back to normal long-term spacing. You can set a new exam whenever you like.

Changing the slider re-plans every topic straight away, using what Re:Call already knows about each one.

Syllabus

Enter each subject's chapters once (a range like 1–14, with optional names). There's a one-click CBSE Class 12 (2026–27) preset with all 79 chapters across Physics, Chemistry, Maths, English, Physical Education and AI, checked against CBSE's official curriculum.

A chapter counts as covered the moment you add a topic for it, or you can mark it by hand. The top card compares chapters per week needed with your pace over the last 2 weeks, says On track or Behind, and predicts when you'll finish. Your deadline is the start of the final sweep, so you finish learning before the last revision round.

Stats

A huge countdown ("101 days left") and a square grid with one tile per day of your study period. Past days glow brighter the more you studied, with the hours written on them. Days you hit your daily goal get a glowing ring. Today is outlined, future days are faint.

Daily goal: set it in Settings (Off, or 1–10 hours, in 30-minute steps). Hitting it builds your streak. Today only counts once you hit it, and an unfinished today never breaks your streak.

Weekly Report

Monday to Sunday: hours, days studied, revisions done and % remembered, each compared with last week. Hours per day against your goal line, each subject marked Best or Needs work (after at least 3 revisions), and a few highlights. Browse past weeks with the arrows. A notification arrives Sunday at 7 pm.

Subjects always keep the same colour everywhere, always shown next to the subject's name:

FSRS (Free Spaced Repetition Scheduler) is an open-source memory model built from millions of real flashcard reviews. It's now the default in Anki, the most popular spaced-repetition app. Re:Call uses version 6 with its published default settings. For every topic it tracks:

R falls over time on a power curve: steep at first, then flatter.

How the next date is picked

1. A new topic starts as "just learned", with a first reminder 1 hour later to lock it in (Brutal adds a 20-minute one first).
2. After that, the next revision is the day your R is predicted to fall to your target (93% on Focused).
3. Your rating updates S and D. S grows more when you remembered something you were close to forgetting, and less for hard topics or ones that are already very strong.
4. In exam mode the date is then capped, swept and load-balanced (Level 60).

The finer details

Where the ideas come from

• Ebbinghaus (1885): the forgetting curve and the spacing effect.
• FSRS-6 by the open-spaced-repetition project: the S/D/R memory model and its default settings.
• Anki's manual: learning steps, Hard/Easy behaviour, and keeping desired retention below 97% (above that, the workload explodes).
• Cepeda et al. (2008), Psychological Science: the best gap shrinks as the test gets closer.

The scheduling engine is a separate, fully tested module (84 tests on Mac). The Windows version is a line-by-line port, checked number-for-number against the Mac engine.

All keyboard shortcuts

Notifications

Switch off anything you don't need

Settings → Features has an on/off switch for every extra. Nothing is deleted; switching back brings it all back. Today, All Topics, Stats, the check-in and the schedule itself are always on.

Your data and backups

• Everything stays on your computer. Nothing goes to the cloud. Mac: ~/Library/Application Support/SpacedRep. Windows: %APPDATA%\SpacedRep.
• Automatic backup every day; the last 14 are kept in a Backups folder.
• Settings → Backup → Export backup… saves one file. Keep a copy on a pen drive or in your email once a week.
• Import backup… asks first and saves your current data before replacing it.
• Moving between Mac and Windows? Export on one, import on the other. Same file format both ways.