↓ a few tools already do this. Each one misses something.

Helperbird
All-in-one suite
~$5/mo

A wide accessibility kit. Fonts, text-to-speech, overlays, OCR, rulers, in every browser.

The trade-offBuilt to do a lot, which means more to learn. The full feature set is behind a subscription.

OpenDyslexic
Font-only swap
Free

A simple, free font swap on every page. Lightweight and open source.

The trade-offDoes one thing well. No spacing, line length, or theme controls, and it runs on every page including code editors.

BeeLine Reader
Color-gradient tracking
Freemium

A soft color gradient down each line so your eye follows to the next.

The trade-offTackles a different angle — tracking, not typography — so it pairs with these tools more than it replaces them.

Lexa
What I built
Free

Full typography control: font, weight, line height, spacing, column width, themes, and reading options.

The differenceStays off on sites where restyling would make things worse, instead of running everywhere by default.

Each of these does part of the job well. The piece that's missing is knowing when not to run.