- Coulomb's law: F = k q1 q2 / r²
- k = 1/(4πε₀) = 9 × 10⁹
- Field lines never cross — why?
- Gauss: φ = q_enc / ε₀ (closed surface only!)
- ⚠ Sphere: E inside = 0 (conductor)
Kopi · by ProSyllabus
The notebook you can't lose.
Photograph the pages you wrote today. Kopi keeps them safe, brings them back to you for revision, and gives you a quiz on what you studied.
Free for 50 pages. ProSyllabus Plus ₹99/month.
Digitise it, so you cannot lose it
Photograph the pages you wrote today. They are kept in your account and you can download any notebook as a PDF. Lose the book, lose nothing.
Revision made for you
You do not plan anything. A page comes back the next day, then after 3 days, a week, three weeks — so you revise it before you forget it.
A quiz made for you
We look at the chapters you have pages in and find a practice quiz on them. You get tested on what you actually studied.
Physics · page 1 of 5 · 1 starred for exam day
A notebook is the one thing you can't buy again.
Books can be replaced. A year of your own working cannot.
Left in the auto, the bus, the libraryThe notes are gone and the exam date is not moving.
Lent to a friend before a testIt comes back late, torn, or not at all.
A bag stolen, a hostel move, rainEverything in one place is everything lost at once.
Two years of notes, one board examClass 11 notes matter in Class 12. Where are yours?
Digitise it once, and it is yours for good.
Every line above has the same answer.
Your notes are always thereOpen them on any phone or laptop, any time. Nothing to carry, nothing to lose.
Download them whenever you wantAny notebook, any chapter, as one PDF in order. Free on every plan — they are yours, not ours.
Last year's notes, still thereClass 11 notes when you reach Class 12. Nothing expires and nothing is thrown away.
Even if you stop payingNothing is deleted. You can still open and download everything — you just cannot add beyond the free limit until you rejoin.
How it works
Two minutes at the end of a study session. The rest happens on its own.
1
Make a notebookName it, pick the exam. "Physics — Class 12", "Quant", "Polity".2
Shoot today's pagesCamera opens, you take four, five, ten shots. Pick the chapter. Done.3
They come back on their ownTomorrow, in three days, in a week: the page is on your screen to revise. You plan nothing.4
You get a quiz on itEach day, a practice quiz on a chapter you actually have notes in.Everything else it does
Backup first. Then the things a backup makes possible.
Photograph today's pages Free
Camera-first. Shoot the pages you wrote today, they are compressed on your phone and filed under the chapter and the date.
Sorted by chapter, on its own Free
Pick the exam your notebook is for. Every page goes under the right chapter, so you can see what you have notes on and what you have missed.
Export as PDF, always Free
Any notebook, any chapter, as one printable PDF in order. The backup is never behind a paywall.
Type short notes too Free
A formula, a definition, a list of exceptions. Typed notes sit next to your photos in the same notebook.
A quiz on what you studied Free
Once you have pages in a chapter, we find a practice quiz on that chapter. What you write decides what you get tested on.
Old pages come back to you Plus
A page returns the next day, then after 3 days, a week, three weeks. Tap "know it" or "forgot" and we adjust. You revise before you forget, without keeping a list.
Star the important pages Plus
On the morning of the exam they are all in one place, in one scroll. Nothing else.
Old photos are never lost Plus
Correct a page and take the photo again. The earlier one is still there underneath, not replaced.
Room for a full year Plus
Free keeps 50 pages in 3 notebooks. Plus takes 1,000 pages every 3 months, in up to 30 notebooks — every subject, with room to spare.
Part of your streak Free
Pages added today show up in your study log and your public study grid, as days you showed up.
Questions written from your pages Soon
Ten questions made from a chapter of your own notes, and doubts answered from the page you point at. Not ready yet.
Free to start. ₹99 a month to keep everything.
The membership is only the notebook. Quizzes and doubts stay on credits, as before.
Free
₹0
- 3 notebooks, 50 pages
- Photos and typed notes, filed by chapter
- PDF export, always
- A daily quiz on what you studied
- Old pages coming back for revision
- Starred pages together on exam day
- Older photos of a page kept
ProSyllabus Plus
Plus
₹99/ month
- 1,000 pages every 3 months, up to 30 notebooks
- Old pages come back, so you revise in time
- Star the important pages for exam day
- Take a photo again, the old one is kept
- Everything in Free
Monthly autopay via Razorpay (UPI Autopay, card, e-mandate). Cancel any time; access runs to the end of the paid month.
Questions
Is my notebook private?
Yes. Pages are visible only to your account. Nothing from a notebook appears on your public profile, in share cards or anywhere else. The only way a page leaves is your own PDF export.
What happens to my pages if I stop paying for Plus?
Nothing is deleted. You can still open, view and export everything. You cannot add beyond the free ceiling until you are a member again.
Is 1,000 pages every 3 months enough?
A student who photographs every page they write in a day fills about 3 to 8 pages. 1,000 in 90 days is over 11 a day, every day. The allowance is a rolling window, so it refills as older pages age past 90 days.
How does the ₹99 membership renew?
It is a monthly autopay through Razorpay: UPI Autopay, a card, or a bank e-mandate. Cancel any time from the Plus page and it stops at the end of the month you paid for.
Do I need the app?
No. It works in the phone browser, camera included. Inside the ProSyllabus app you can view and add pages; the membership is bought on the website for now.
Is anything sent to an AI?
Not today. Filing, revision scheduling and the daily quiz pick are plain rules on our server. If we add AI features on your notes later they will be opt-in, and the privacy notice will say so first.