Your homework, marked in red, with hints.
Snap a photo of the page. Every mistake gets a mark where it is and a hint toward the fix, not the answer. What you got right is marked too.
Take a photo of one page, straight on, in good light.
Marked in three steps
Snap the page
One page, straight on, in good light. Say what the assignment was if you like.
It works every problem
RedPen solves each one itself first, then compares with yours, step by step. Unclear writing is flagged, not guessed.
Fix it yourself
A red mark where each mistake is, and a hint toward the fix. The answer waits behind a button for when you've tried.
Questions
What kind of homework does it mark?
Anything with a worked answer on the page: math from Grade 3 to university, physics and chemistry problems, short written answers. One page per photo, in a JPG or PNG, straight on and well lit. Handwriting is fine.
How does it decide what's wrong?
RedPen reads each problem, solves it on its own before looking at your answer, then compares the two step by step. It names the first step where yours goes wrong and writes a hint about that step, not the answer. The answer is there behind a button if you want it.
What if it can't read my writing?
Then it says so. A problem it can't read clearly is marked as unclear, in grey, never as wrong. A clearer photo, or writing a little larger, usually fixes it.
Are the red marks always in the right place?
They point at your final answer for each problem and are usually close, but not always exact. Each mark is numbered to match the list beside the page, which is what carries the meaning. If a mark lands in the wrong place you can hide it with one tap.
Does it give me the answers?
Not unless you ask. Hints come first, so you can fix the step yourself. Every problem has a Show the answer button for when you've tried.
Is it free?
Yes. RedPen is free with a Knomi account. Every marked page is saved to your account with its own address.
The same mistake keeps coming back?
Knomi is a personal tutor for every student. It teaches one topic at a time, and when something doesn't click it goes back to the earlier skill behind it and fixes that first.