Osmanthus

A desktop RSVP speed-reader for epub files.

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What is RSVP?

Rapid Serial Visual Presentation (RSVP) flashes one word at a time in a fixed spot on screen. This eliminates the saccadic eye-movement — the time your eye spends jumping between words — which is the main speed bottleneck in conventional reading.

Osmanthus also uses the Optimal Recognition Point (ORP): the letter ~30% into each word where the brain recognises it fastest. That letter is highlighted in red and aligned to a fixed horizontal column so your eye never drifts.

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Features

• ORP highlighting — the recognition-point letter is coloured red and horizontally locked
• Adjustable WPM — 60–1500 words per minute; fine-tune with keyboard shortcuts
• Epub import — drag & drop or file picker; covers, titles, and authors extracted automatically
• Table of contents — browse and jump to any chapter by header; navigate with ↑ ↓ Enter (H)
• Paragraph context — see the current and previous paragraphs at any time (P)
• Zen mode — hide all chrome for distraction-free reading (Z)
• Fullscreen — native macOS fullscreen (F)
• Font scaling — resize the word display from 0.5× to 3× ([ ])
• Undo history — step back through scrubber drags, TOC jumps, and word skips (⌘Z)
• Command palette — search and open any book instantly from anywhere (⌘K)
• Ramp-up mode — gradually accelerates from 50% to full WPM over 5 seconds on play (above 500 WPM)
• Reading timer — set a countdown in seconds; ticks down in real time, pauses automatically when it expires (T)
• Auto-save — progress is saved every 25 words and on exit
• Dark / light mode — follows your system preference; toggle manually with D

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Screenshots

Empty library	Library
Reader	Zen mode
Library shortcuts	Reader shortcuts

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Download

Grab the latest .dmg from Releases.

macOS note: Osmanthus is unsigned. macOS will block it with a "damaged" error. Move the app to Applications, then run this in Terminal:

xattr -cr /Applications/Osmanthus.app

Then open it normally.

Apple Silicon only (M1/M2/M3/M4). Intel Macs can build from source.

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Keyboard shortcuts

Library

Key	Action
N	Add book
↑ ↓ ← →	Navigate books
↵	Open selected book
⌘⌫	Remove selected book
⌘K	Search books
D	Toggle dark / light mode
I	About
/	Keyboard shortcuts

Reader

Key	Action
Space	Play / pause
← →	Skip ±10 words
⇧← ⇧→	Skip ±50 words
↑ ↓	Speed ±20 wpm
⌘⇧← ⌘⇧→	Previous / next paragraph
C	Toggle context words
N	Toggle navbar
X	Toggle player controls
[ ]	Font size −/+
P	Paragraph view
H	Headers / table of contents (↑ ↓ Enter)
Z	Zen mode
F	Toggle fullscreen
G	Go to word #
W	Set WPM
S	Set font size
R	Toggle ramp-up (WPM > 500 only)
T	Set reading timer
U	Toggle undo history
⌘Z	Undo word index change
⌘K	Search books
D	Toggle dark / light mode
I	About
L	Go to library
Esc	Exit fullscreen
/	Keyboard shortcuts

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Build from source

Prerequisites: Rust, Node.js 18+, pnpm — see SETUP.md for full instructions.

pnpm install
pnpm tauri build
# Output: src-tauri/target/release/bundle/macos/Osmanthus.app

For a specific architecture:

pnpm tauri build --target aarch64-apple-darwin   # Apple Silicon
pnpm tauri build --target x86_64-apple-darwin    # Intel

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Planned features

• An android build!

Yep that's all I'm planning for now lol.

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Contributing

Note: This codebase was written primarily with the assistance of large language models (Claude). It is functional and tested, but has not yet been fully audited or refactored by a human contributor. It is currently in beta while I build a deeper understanding of the internals.

If you want to contribute or understand how everything fits together before diving in, see INTERNALS.md — It documents the tech stack with learning resources, maps every feature to its source files and line numbers. It calls out the patterns most likely to bite you.

The LLM-oriented codebase guide is in CLAUDE.md.

My personal progress on understanding what I've built is in INTERNALS.md

Issues are welcome! At the moment PRs are not. Since this code was heavily AI generated I don't think I understand it well enough to take contributions. This will hopefully change at some point in the future :)

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License

MIT — see LICENSE.