This extension is good, but has the following drawbacks:
1、No dark mode.
2、No multi-language support.
3、As per the instructions provided by the author seven years ago (ReFont menu > Show More > Site font > Default font), I did not see "whitelisted".

You can apply niche font types that are installed on your local computer, by adding correct full names of them into the library.

I like this extension because there are hundreds of fonts to choose from. However, it can be really buggy at times. Whenever I want to add a font to my library, it resets and I have to go find it again.

By the way, to anyone who says the extension doesn't work, try opening and closing it repeatedly until it actually lets you choose your font. I was confused at first, but this worked for me. However, this shouldn't really be an issue in the first place and needs to be fixed. I've found myself opening and closing the extension 5 times in a row to get it to do what it's supposed to.

Only says "loading"

Mostly doesn't work. The app just says "Loading" with no progress bar, so I don't know if it's actually loading or not. Other one star reviews have complained about the same thing, but they are several years old, so I thought the problem would be fixed by now. It hasn't.

A few times, I did get it to load, but I don't know how. I was able to change the font of every website, but I wanted to change the font of a specific website. Maybe ReFont can do that, maybe not. I wasn't able to experiment with it because of the "Loading" problem.

I can load Noto Sans, but not UnDotum, which is distributed by KLDP on Firefox Nightly for Android.

fonts work pretty well but in the rules section, it only allows one custom rule? there's no button to add additional rules

Need the ability to select ALL FONTS to add them to the available library. Also, the lag in "loading" the font selections through the toolbar icon is INSANE. I've used extensions like this previously in other browsers and have never seen a lag this bad. Please address these two issues on the next update. Thank you!

it doesn't do anything. just keeps loading.

First, before I had 4 star review. Now I can only give 3 stars.

The extension is of great help, but it's Font "install" UI is a catastrophy. Why can't I just automatically have an option to choose from toobar-icon pop-up window a local font like with native applications (incl. FireFox [e.g. Setup default fonts selection). From a dialog that would list all local fonts by name, then has small list where you can see that fonts supported versions (cursive, bold, etc.), size - and the dialog would show how the current selected font would look like. That would be awesome, and it should not need installing manually fonts to the extension.
And that could be even optional alternative you would need to choose from setup, you could still default to what it's now.

AND, my first review complained about the cumbersome font "install" system - back then I didn't even understand it, but although I know how to use it now, but it's a total PITA to use. Still haven't fixed that, I posted the last long ago.

So, thank you, but I can't give you more, even if it's the best I've found to this kind of thing.

Also, feature request:
Could you add an option to force the whole page or site to make sure that possible font ligatures are being enabled through the page? I want many pages to rendered with a cool monospace font - I used IBM 3270 terminal font before, but now I use Fira Code, and the reason I switched was that though IBM 3270 looked better to me, so awesome and retro, but Fira Code ligatures blew my mind, and I want them!

The extension does not work for no obvious reasons almost 100% of time. It keeps loading something infinitely.

Please stay on Up to dated.

Plus: allows to use local fonts (only you have to type their full names for some reasons).

Minuses:

- constantly randomly breaks: you see "Loading" and nothing else in the extension popup.
- I wish there was a way to add/remove/edit rules inside the extension.

It's super good for allowing us to use local font!
But it truely will stuck on "Loading" randomly, a way to solve this is to open its menu and click on the button on the top right to switch it off, then close its menu, then open its menu again and switch it on, then possibly you will see the drop-down menu for choosing the font.

Claims you can import font from your computer, but has no such option

EDIT:

It turns out you can, but it's really tricky due to the UI

Great :D Thanks https://addons.mozilla.org/fr/firefox/user/13230872/

This is an add-on that absolutely deserves five starts, but isn't getting it because the amount of times I nearly broke my finger from having to close and re-open the add-on over and over again just to get the stupid thing to load. Because when it says it's "loading", it's absolutely not and is just stuck in limbo. You could wait eons but it's never going to happen, so you just have to keep closing and re-opening it in hopes that the options it gives you will eventually show up. Please update and fix this... this add-on literally has so much potential but is held back by this minute yet infuriating flaw. Not to mention, the ability to import rules from an export does not work either.

Finally I can change a few sites that use material design fonts with stupid arrows and symbols without changing my global settings to prevent the horrible antialiased fonts most use from ruining my eyesight! Thank you sir!

Firefox 78: I see only "Loading", when I click the ReFont button. Cannot change font. :-(