Demo #2 — Spaced PDF Emails (spaced repetition for PDFs)
I read a lot of PDFs—books, essays, playbooks, internal docs, random longform links saved as PDFs—and I kept running into the same problem: I’d finish something, feel like I “got it,” and then a week later I couldn’t recall the key ideas.
Flashcards solve this for facts, but long PDFs don’t fit cleanly into a card-based workflow. So I built Spaced PDF Emails: a lightweight PDF library that uses spaced repetition to bring the right document back at the right time.
What it does
At a high level, the app helps you do two things:
- Store and manage a library of PDFs
- Schedule reviews automatically (and remind you by email)
How it works (the mental model)
Each PDF lives in a box (a simple Leitner-style system). The box represents how “solid” the document is in your memory.
- Box 1 = new / not yet learned
- Higher boxes = you’ve reviewed it successfully multiple times
- Each box has a review cadence (short intervals early, longer intervals later)
Every PDF also tracks:
- Last Review (when you last reviewed it)
- Next Review (when it’s due again)
That’s the key idea: you don’t have to guess what to revisit—the schedule is explicit.
Walkthrough of the UI
Library page
- Upload a PDF via drag-and-drop (or “browse files”).
- The PDF appears in your library with:
- Name
- Box
- Last Review
- Next Review
- You can delete items you don’t want to track anymore.
Even without doing anything else, this view gives you a quick dashboard of what’s due (or overdue) and what can wait.
Review flow (conceptually)
The intended workflow is simple:
- Open the items that are due.
- Review the document (skim highlights, re-read key sections, etc.).
- Mark the review outcome (e.g., “good / hard / again”), which adjusts the box and automatically recalculates the next review date.
Why email reminders?
The main failure mode with any spaced repetition system isn’t the algorithm—it’s forgetting to show up.
So the “Emails” part is intentional: instead of needing to remember to open the app, you can receive a periodic reminder containing the PDFs that are due. The app becomes something you can keep up with in a few minutes per day, rather than a backlog you avoid.
What I’m using it for
This is especially useful for:
- “I want to remember this” PDFs (career, leadership, product, investing)
- Books and long essays you’d like to internalize over time
- Any doc you don’t want to disappear into a bookmarks graveyard
What’s next
A few obvious upgrades I’d like to add:
- Search + tags/collections (e.g., “Leadership”, “Product”, “Investing”)
- Better review UX (quick actions, notes, and a cleaner “due today” queue)
- Import/export so the library isn’t trapped in one place
- Smarter scheduling customization per box
If you’re someone who hoards PDFs and wishes they actually turned into retained knowledge, this project is my attempt at a simple fix.