Opal fuses handwritten notes, linked markdown, and spaced repetition into a single app. Opal is the tool that lets you discover, capture, and connect the irreducible ideas inside what you know.
Every idea you learn can be decomposed into smaller, irreducible units — atomic notes. Each atom holds one clear concept. Linking atoms together forms a chain of thought: the path your mind takes when it truly understands a subject.
The act of decomposition is the act of learning. When you force yourself to isolate a single idea and write it in your own words, you move it from recognition to deep recall. Each atom has a stability score that reflects how well you've internalized it.
When you connect one atom to another, you're encoding the relationship between ideas — the same structure your brain uses to retrieve them. The more links an atom has, the more paths your mind can follow to reach it.
Four capabilities. One principle: the understanding has to be yours.
Three actions. One seamless loop.
Because context switching kills retention. Opal brings everything into one place.
| Opal | Obsidian + Anki | GoodNotes | Notion | |
|---|---|---|---|---|
| Markdown editor | ✓ | ✓ | — | ~ |
| Apple Pencil handwriting | ✓ | — | ✓ | — |
| Spaced repetition | ✓ | ~ | — | — |
| Knowledge graph | ✓ | ✓ | — | — |
| Ink inside markdown | ✓ | — | — | — |
| Cards from notes | ✓ | ~ | — | — |
| Local-first / offline | ✓ | ✓ | ✓ | — |
| Single app | ✓ | — | — | — |
We're recruiting for our closed beta. Free while we're building. Your feedback shapes the product.