My Hacking Adventures with Safari Reader Mode

I use a custom hack on top of this chrome extension ... https://chrome.google.com/webstore/detail/mercury-reader/okn...

It works pretty neat.

I also came across this extension last week, https://github.com/Kenshin/simpread ... it's in chinese and perhaps a bit bloated for my use cases. But, it looks pretty good. I would auto translate the comments in the code to English before using.

I'm not sure where you can get the current code for Safari's Reader Mode but interestingly, it was based on the original Readability.js code, created and open sourced by a development shop called Arc90 [0]. As you noted, Firefox was also based on Readability (in the repo you linked to, you can see that it's copyright 2010 by Arc90). By this point both browser implementations may largely have been rewritten. Arc90 was acquired (oddly, by a short-lived EDM festival promoter called SFX), and its founder later started another agency called Postlight which created a similar extension for Chrome called Mercury Reader [1].

[0] https://jaxenter.com/safari-5-reader-based-on-open-source-re...

[1] https://postlight.com/insights/the-postlight-mercury-platfor...

It’s a write-up describing a bypass of Single Origin Policy in Safari’s Reader View. Just a blog post, and it mentions that vulnerabilities are fixed in the August 2020 update