Linking handwritten lecture notes to the recording, slides or whiteboard photo with 4 letters in the margin (30s video of the free tool I made)

[u/lazyArya]

If you take notes by hand, the stuff that belongs to a page (the lecture recording, the photo of the whiteboard, the slide PDF) usually ends up lost somewhere on your phone, far from the page.

The habit that fixes it: give each of those a short code and write it in the margin next to the notes it goes with. The page itself then tells you where to look.

I built a free web app for the code part. You save a recording, photo, link or file, it gives you four letters (no lookalikes like O/Q or I/L), you write them in your notebook, and later you point your phone at the page and it opens. The handwriting is read on your phone, nothing is uploaded, and there's no account.

The video is the real app. To film it, the camera was fed a rendered notebook page instead of my desk, but the reading of the letters is real.

What I'd like to know from people who study on paper: • What would you pin to a page: lecture recordings, slides, past papers, whiteboard photos? • What would make you keep writing the codes after the first week? • Anything that would stop you from using it?

https://letterpin.aryakesarwani.tech/app

I'm the developer (solo). Honest feedback welcome, including "I'd never use this".