Meet Cramby: a study companion that knows what you don’t know yet

Most study tools are good at one thing: turning material into more material. Upload a PDF, get a summary. Paste notes, get fifty flashcards. The pile gets bigger, and the hard part is still yours: knowing what you actually understand, what you only recognise, and what to do with the evening you have left.

Cramby is built around that hard part.

The problem with study apps#

Reading a clean summary feels like learning. So does scrolling through flashcards you made an hour ago. Both create familiarity, the comfortable sense that you’ve seen this before, and familiarity is exactly what fools students into stopping too early. What predicts exam performance is whether you can produce an answer from memory, days later, when the question is phrased a little differently.

So the question we kept asking was not “how fast can we generate notes?” It was: after the first upload, how does Cramby work out what this student doesn’t understand yet, and what should they do about it today?

What Cramby does#

1. 1

   Turns your material into a lesson

   Record a lecture, drop in a PDF, slides or a YouTube link, and Cramby writes a short course from it: sections in a sensible order, examples, and a check after each part.
2. 2

   Tracks what you know, concept by concept

   Every answer you give, in a quiz, on a flashcard or inside a lesson, updates your mastery of the concept it tested. You see each idea move from Attempted to Familiar, Proficient and Mastered.
3. 3

   Notices why you get things wrong

   A slip on something you usually know is different from a misconception, and both are different from a gap you never learned. Cramby tells them apart and practises each one differently.
4. 4

   Plans backwards from the exam

   Add an exam date and Cramby builds a day-by-day plan: new material first, practice at growing gaps, and a short mock on the last day. Miss a day and the plan rebuilds from where you are.

And when you just need help, there’s a tutor that has read your notes. It explains, quizzes you back, finds a video when a diagram would help, and only changes your lessons when you say so.

The science underneath#

None of the ideas Cramby leans on are new. They’re some of the best-replicated findings in learning science, and most students have never been told about them:

• Retrieval practice: pulling an answer out of memory strengthens it far more than reading it again.
• Spacing: reviewing at growing intervals beats cramming the same total time into one night.
• Interleaving: mixing problem types teaches you to recognise which method a question needs.

Flashcards run on FSRS, a modern open-source scheduling algorithm, tuned so you remember about nine cards in ten when they come due. Concept mastery is tracked with a rating model of the kind used in adaptive practice systems, and the levels you see are deliberately simple so you can tell what they mean at a glance.

Cramby, by Clerval#

Cramby is made by the team behind Clerval. Clerval is a general AI assistant; Cramby is the focused study companion that sits beside it. If you already use Clerval, you’ll recognise the care for the details: the same attention to speed, privacy and interfaces that stay out of your way.

Try it on your next lecture#

Cramby is free to start, with no card needed. Paid plans add more lessons, deeper explanations and longer podcasts, from $11.99 a month, or less when you pay yearly. You can use it on the web today, and the desktop and phone apps are on the way.