Bionic Reader од Joetommy

Bionic Reader transforms text on any webpage into "bionic reading" format: it bolds the leading portion of each word so your eyes have a fixation point to anchor on, which helps you read faster with less effort.

Turn it on for every site by default, or flip it on just for the pages you want. Adjust how much of each word gets bolded from the popup.

Built to leave everything else about a page alone: original layout, design, and structure stay untouched, and it backs off automatically on pages that are already doing things with their own text (like collapsible sections) rather than breaking them.

Fully open source, so you can read exactly what it does: github.com/Joetommy/bionic-reader