Project Gutenberg Outline by underscore-developers

Project Gutenberg Outline turns long Gutenberg books into something you can actually navigate.

Open a book on gutenberg.org and the extension builds a structured outline plus a right-edge timeline so you can move by chapter, subsection, or scroll position.

Features

• Hierarchical outline — parts, chapters, and subsections, detected from headings and numbered paragraphs
• Timeline scrubber — slim tick rail on the right; hover for a preview, mouse wheel to step one-by-one, click to jump
• Split peek — Shift+click an outline row or tick to read a passage without losing your place
• Return to reading spot — outline jumps stack your previous scroll position (Alt+Left Arrow)
• Built-in book dark mode — darkens the Gutenberg page for night reading; toggle with the moon button or press D (preference is saved)
• Search — filter the outline by chapter title or quote text

Shortcuts

• Ctrl/Cmd + \ — open or close the outline drawer
• D — toggle book dark mode
• Alt + Left Arrow — return to previous reading spot

Privacy

• Runs only on Project Gutenberg book HTML pages
• Permission: storage (dark-mode preference only)
• No accounts, analytics, remote code, or network calls

Notes

Designed for *.gutenberg.org cached EPUB HTML and /files/ book pages. Outline quality depends on each book’s heading structure; long unheaded stretches are auto-chunked.