Hi pjcamp, thank you for your report.

This extension makes a change to how Firefox requests images, but many sites ignore the change. If there is a specific site you want to mention, you can contact me by creating a new Github issue on https://github.com/jscher2000/dont-accept-webp/issues or emailing jscher2000@outlook.com.

On the other hand, if it fails on every single site, check for this issue: https://support.mozilla.org/kb/extensions-private-browsing

There also are some pages that give Firefox multiple format options (picture tag/source tags) and it selects WebP for some reason. I don't have a fix for that yet.

Hi, sites decide what format to serve based on different criteria. This extension only changes the "Accept" header. Some sites check the user agent instead (to see whether it's a modern browser). If you had the problem with a post on the Community tab of a YouTube channel, I see it, too. I don't think Google offers those images in alternate formats. (If I try to download one using the Internet Explorer 11 user agent, I still get WebP.)

Hi, there is one new permission in version 0.9, the "management" permission, which allows checking the names of your installed add-ons and whether they are enabled or disabled. You can see the added code in the comparison page on Github: https://github.com/jscher2000/dont-accept-webp/commit/25eea9332a3819f5d0c9c224b7178bd3db830694

If anyone prefers to install the previous version, you can grab it from the All Versions page at: https://addons.mozilla.org/firefox/addon/dont-accept-webp/versions/

And if you do not trust me, don't run my add-ons.

Actually, this add-on has ALWAYS needed and requested the "< all_urls >" permission in order to modify requests to websites. That is *not* new, but probably you have become more security-conscious since you originally installed it. We should all be careful, and there is a support article on this: https://support.mozilla.org/kb/tips-assessing-safety-extension

If anyone prefers to install the previous version, you can grab it from the All Versions page at: https://addons.mozilla.org/firefox/addon/dont-accept-webp/versions/

(What *is* new in version 0.9 is checking whether you have another add-on known to have a conflict with this one.)

For what it's worth, I still have no interest whatsoever in what you are doing in your Firefox, and there's no way for me to know because this add-on still doesn't send me any data. If you don't believe me, then don't use the add-on.

Hi Niklas, if you right-click > Open Image in New Tab before dragging, the tab should tell you the true format (hold your mouse over the tab to see the full tooltip).

You can test using https://i2.wp.com/radical-mag.com/wp-content/uploads/2019/08/@Test-BMW-320d-8.jpg -- normally, if you hover your mouse over the tab, it will say it is a WEBP image; with the extension enabled, it should be a JPG image.

If it doesn't work on that one, check whether it's the private window issue: https://support.mozilla.org/kb/extensions-private-browsing

If you want to send me some problem URLs, you can create an issue at https://github.com/jscher2000/dont-accept-webp/issues or email me at jscher2000@outlook.com.

You can test using https://i2.wp.com/radical-mag.com/wp-content/uploads/2019/08/@Test-BMW-320d-8.jpg -- normally, if you hover your mouse over the tab, it will say it is a WEBP image; with the extension enabled, it should be a JPG image.

If it doesn't work on that one, check whether it's the private window issue: https://support.mozilla.org/kb/extensions-private-browsing

If you want to send me some problem URLs, you can create an issue at https://github.com/jscher2000/dont-accept-webp/issues or email me at jscher2000@outlook.com.

What this add-on does is remove a signal that Firefox normally sends to the server that your browser can handle WebP images. The idea is to discourage the server from sending WebP in place of JPEG or PNG.

I'm not sure what problem you ran into with saving an image not working, but do you mean you still got a WebP image? That definitely can happen when the site insists on sending you one, or when the page is using a "picture" tag, but this add-on should help on most sites.

If you need an add-on to convert a WebP image to something else, check out https://addons.mozilla.org/firefox/addon/save-webp-as-png-or-jpeg/

That's strange. Disabling the extension should prevent it from making any changes. Any chance that the "image.webp.enabled" preference somehow got set to false in about:config? (I don't recommend setting that preference to false.)

From what I can see, 9gag uses a newer method of image substitution: a picture tag listing both webp and jpg options, and Firefox is choosing webp. This extension can't help with that issue. Currently, I recommend behind! to work with that design: https://addons.mozilla.org/firefox/addon/behind/

When you enable the extension (stop sign showing) the Accept header should no longer list image/webp. You can check on https://www.jeffersonscher.com/res/jstest.php When you disable the extension (yellow warning triangle is showing), the extension doesn't strip out image/webp.

If yours doesn't work either way, I can think of two possible reasons:

(1) You are using a private window but didn't enable the extension to run in private windows. In this case, the stop sign/triangle toolbar button will be missing. See the following article to fix this problem: https://support.mozilla.org/kb/extensions-private-browsing

(2) There is a conflict between this extension and another extension or proxy that also modifies the Accept header. This could be hard to track down.