Read, annotate & connect

Bifolium reads and annotates Markdown, from your own files or straight from GitHub. Open a document on iPhone, iPad, or Mac and it is read where it is, without importing or converting it.

Bifolium's Paper reader on iPhone showing Notes from Bellwether Island with a highlighted sentence — Paper

The same page in Bifolium's OLED appearance on iPhone, pale text on black — OLED

Bifolium's Paper reader on iPhone rendering a Mermaid flowchart from opening a document to adding a note

Whatever Markdown you have.

Bifolium detects the Markdown a document is written in and renders it correctly: CommonMark, GitHub Flavored Markdown, and Obsidian's flavor with wikilinks, callouts, and YAML frontmatter.

Every detail, offline.

Tables, images, footnotes, TeX math, and Mermaid diagrams render without a connection. Code is highlighted in more than 30 languages.

Keep the line. Keep the thought.

Highlight a passage and note a thought beside it. Both are kept apart from the document, so reading never changes the file.

Bifolium edits, too. When a file needs a change, open it in Source or Live Preview and save it in place.

Bifolium on iPhone in the OLED appearance, with a highlighted passage and a note beside it

Bifolium's Highlights Library on iPhone in the Paper appearance, listing quotes and notes from several documents

Every highlight, one library.

Every highlight and note, from every document, in one place. Search across them, or start from one highlight and see related passages from your other files. Matching runs on your device.

Export a document to PDF or HTML, or your highlights and notes to Markdown with links back to each passage.

The page, the way you like it.

Four themes come built in, or make your own. Set type size, line height, text width, margins, and paragraph spacing to suit the screen in your hand.

More room on iPad and Mac.

Bifolium's Paper reader on a landscape iPad, with a highlighted passage and its note visible together

Your files, wherever they live.

Save GitHub repositories, public or private, as read-only snapshots you can read offline and refresh when you choose. On a Mac, pick files or folders to carry to iPhone and iPad through your own iCloud; highlights, notes, and reading position stay in step.

Bifolium needs no account. Rendering, search, and matching run on your device. Sync uses your iCloud account, and GitHub connections go directly to GitHub. Analytics are off unless you turn them on.

Bifolium's Mac workspace in OLED, with Documents on the left, Notes from Bellwether Island in the center, and Highlights on the right

Thirty days to read.

The first document you open starts a 30-day trial of the whole app. Every feature, no card.

Then it's yours.

Permanent access: $19.99
Or monthly: $2.99 a month

Prices in USD. Same app either way. If access ends, your originals stay where they are and your highlights and notes remain yours to export.