Folio: Handwritten Notes and a PDF & EPUB Reader, Open Source

Some people think with a pen. Most note apps treat handwriting as an extra, and most readers treat annotation as an afterthought. We wanted one app that feels like paper, opens instantly and keeps everything on your tablet or phone, so we built Folio and released it as open source.

What it does

Folio is an Android app for handwritten notes and for reading PDF and EPUB books with a pen in hand.

Write naturally

• Twelve brushes, from ballpoint and fountain pen to pencils, highlighter, chalk and a paint brush.
• Low-latency ink with pressure and tilt, and pressure curves you can shape yourself.
• 35 page templates, from lined and Cornell to planners and music staff, or an infinite canvas.
• Layers, lasso, shapes, text, tables, stickers, images, a ruler and voice notes.

Handwriting to text

• Select your handwriting with the lasso and convert it to typed text, in 300+ languages, on your device.

Read with a pen in hand

• Open PDF and EPUB books, write on PDF pages and highlight, underline and bookmark.
• Search, browse chapters, and export the annotated PDF or your reading notes as Markdown.
• Study view: a book and a notebook side by side.

Live boards for calls

• Whiteboards built on Excalidraw, written with your pen. Share a link and people in your call can watch and draw from any browser.

Your notes stay yours

Folio works offline and your notes and books never leave your device. There is no account and no advertising. Notes are saved in an open format (.folio) you can always take with you, and backups go to a folder you choose.

Get it

Folio is coming to Google Play. Until then you can build it from source: the code, setup steps and the project website are in the GitHub repository and at folio.allient.io.

Why we open-sourced it

A note-taking app holds personal things, so people should be able to see how it works. Open source also lets anyone report a bug, suggest a feature or contribute. If Folio is useful to you, a star on GitHub helps others find it, and you can see everything else we publish at github.com/allient.