Got a stack of books you bought but haven't read? Same.
TsunDrop is a reading app that stacks every book you buy into a physical tower — powered by a real 2D physics engine.
You don't have to read them. Just stack. That's the whole point.
— Just stack. That's it. —
Every time you add a book, it falls from the top and lands on your tower, sized by its format (bunko, shinsho, hardback, A5). The physics engine makes every stack a little different. Same book, different lean.
Reading apps love to make you feel guilty. TsunDrop doesn't. Buying books — even ones you'll never get to — is a perfectly valid hobby. We're here to celebrate it.
— Who it's for —
- People who buy books faster than they can read them
- Anyone who hears "your tsundoku is too big" and thinks "let it grow"
- Readers who want to see their pile, not just a number on a screen
- Folks burned out by every other reading tracker
— Inside —
▸ Stack (the main thing)
Scan a barcode or type a 13-digit ISBN. TsunDrop pulls bibliographic data from openBD and Japan's NDL Search. Manual entry works too.
Books fall in, get stacked, lean against each other. Add more and the pile grows taller, genre colors mixing into a mosaic. Whether that's "too many" or "looking great" is entirely your call — set the overflow warning to "none" and stack as much as you want.
▸ Height Rank
The total spine width of every book — read or unread — is measured against a real-world scale.
An apple → a milk carton → a ruler → a cat → a guitar → an adult → a phone booth → a giraffe → a house → a big tree → Tokyo Tower → Mt. Fuji → Everest.
Buy and stack: rank goes up. Read: rank goes up. Both count, equally.
▸ Read one when you feel like it
Tap a book, hit "Finish & shelve." It moves to your Finished Shelf, sortable by date, title, or color. The books resting on top tumble down in physics. That moment is satisfying — but it's a side dish, not the main course.
▸ Numbers
Tower view: unread count / pages left / pages read
Shelf view: total pages read / books finished / shelf width (cm)
Pages stack up like XP. Set a monthly goal if you want. Skip it if you don't.
▸ Share
Export your tower as a 1080×1080 image and post it. "Yeah, I haven't read most of these."
— Details —
- Genre colors (literature, history, philosophy, tech, business, other)
- 3 text sizes, 4 themes (Green, Ink, Navy, Grape)
- Haptic feedback
- Notes on every book (up to 2000 characters)
- Export and import for backup
— Privacy —
All your book data stays on your device. No account required.
TsunDrop only contacts openBD and NDL Search for bibliographic lookups. Nothing else leaves your phone.
The camera is used solely to scan ISBN barcodes.
— You might be here because —
Your shelf is overflowing.
You buy too many e-books and forgot what you have.
You want a break from "you really should read more."
If so: just stack. Read when you feel like it.
Stack first. Read later (if ever).
Bibliographic data: openBD / NDL Search
Licenses: Matter.js (MIT) / Noto Serif JP, Noto Sans JP (SIL OFL 1.1)
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