Read Flow 0.4.0 adds highlighting and drawing, bookmarks, a readability score, and a much sharper bionic reading mode. Citation saving now lives in ScholarSail's separate Cite Keeper extension. There is still no account, telemetry, advertising, or developer-operated service.

New in this version:
- Highlight text in six colors with Alt+Shift+H, the right-click menu, or the popup, and click a highlight to recolor or remove it. Highlights never change the page's own markup, so they work alongside bionic reading and Guide Me.
- Draw on any page: Alt+Shift+D opens a toolbar with a pen, a translucent marker, a text highlighter, and an eraser, with undo and clear. Drawings scroll with the page, and highlights and drawings both reappear when you return to it.
- Bookmark your place: Alt+Shift+B marks the first line on screen (or the text you selected), and the right-click menu's Add Bookmark Here marks the line you clicked. Jump back from the popup's new Bookmarks section, or from All bookmarks, which lists every bookmarked page and reopens it at the spot. Bookmarks follow the text, so they land on the right line even after the page reflows.
- Score readability: the new Readability score section rates the page, a selection, or pasted text with Flesch reading ease, an average US grade level, and five grade formulas.
- Sharper bionic reading: choose light, balanced, or strong emphasis; hyphenated words and words split by links or formatting are emphasized correctly; accents are never split from their letters; scripts where partial bolding breaks the lettering (Arabic, Hindi, Chinese, and others) are left as written; and light or medium page text gets clearly visible emphasis. Turning it on no longer freezes long articles.
- Set the reading ruler's height.
- Citation saving has moved to Cite Keeper. The Sources & citations section now links to it, and sources saved by an earlier version stay in Read Flow's library so they can be exported as a JSON backup and imported into Cite Keeper.