Yesterday I received a batch of pictures from a customer that I was supposed to exchange on her website. In the first email I thought the files were defective because the images were not displayed in Apple Mail and only strange placeholders with question marks were visible in the mail. I only knew that from broken JPEG photos.

I asked the customer to send me the files again, but the second email looked the same. When I looked at the attachments with the paper clip symbol in Apple Mail, I saw the file extension "webp" and it was already clear to me: that is the reason for the display problems. As a result, my Apple Mail was smeared less than 5 seconds later - probably because it was so shocked to discover "WebP" files.

In Apple Mail, WebP files look like they are broken image files. It didn't look any better in the second email from my customer.

Mac crash due to WebP?

[Fun mode] The reaction of my MacBook Pro is understandable, since the WebP format was created by Google and Apple of course has to refuse to cooperate. For this reason, macOS probably has a random crash sequence built into it, which is started whenever you want to open a WebP file on the Mac. [/ Fun mode]

With the help of the WebP image format, photos and graphics with small file sizes can be saved and websites load significantly faster. By the way, Sir Apfelot also runs a tool that makes the images available as WebP if the browser can use them.

WebP is Google's HEIC

While Apple is relying on a new compression system from its own home with HEIC, Google has a reduction in all graphic and photo files on the web on its agenda with the WebP standard. Unfortunately, WebP is (not yet) natively supported by Apple's operating system, so that interestingly, although the files are displayed in Quicklook (highlight the file and press the space bar), they cannot be opened in the preview.

If you want to read more about the compression technology of WebP, you will find a suitable document from Google here: Compression Techniques (of WebP).

Quick help: WebP ad with Google Chrome

If you just want to take a quick look at a WebP file, you can also use the Google Chrome browser. This of course understands the image format and displays the graphics accordingly. Quicklook also seems to be able to handle the files (at least for me). But changes cannot be made with it.

In this post, you will learn how to open, modify, and convert image files in WebP format with your Mac.

In this post, you will learn how to open, modify, and convert image files in WebP format with your Mac.

Modify and convert WebP files on Mac

I now had to get the files in a format that I can open in Photoshop. At the time of Mojave, I once installed a Photoshop plug-in that enables the import of WebP files (see here). Unfortunately, when I switched to Catalina, the plugin became unusable because I only get a message that the "WebPFormat.plugin" plugin is not from a verified developer and therefore cannot be opened.

My WebP plugin for Photoshop is slowed down by the security mechanisms of macOS Catalina.

My WebP plugin for Photoshop is slowed down by the security mechanisms of macOS Catalina.

You could do it here switch off the gatekeeper of the Mac with terminal commands, but I try to avoid interfering with the security settings of macOS as much as possible and have therefore started looking for other options.

1st possibility: XnConvert - does not work

The first round of Googling brought me to a free app called "XnConvert", which can be found in the Mac App Store. The first impressions were also positive: The files were all opened and displayed correctly, but unfortunately something went wrong every time during the export and strange artifacts arose in some parts of the image.

Here you can see the artifacts that were created during the export with XnConverter (graphics: Sir Apfelot).

Here you can see the artifacts that were created during the export with XnConverter (graphics: Sir Apfelot).

Even after trying out the settings a lot, the defective parts of the image did not disappear, so that XnConvert can unfortunately not be recommended at this point.

2nd possibility: GraphicConverter - a direct hit

My second idea was "GraphicConverter"by Lemke Software. A tool that I used more than a decade ago to convert large amounts of images from one format to another. A quick look at the types of files it can import and export, showed me that I was at the right address: GraphicConverter supports WebP both when opening and saving.

So I got the test version, which is fully functional and only differs from the full version in that there is a waiting time when starting the program.

Opening the WebP files went smoothly. All images that were dragged and dropped onto the program icon were immediately displayed in the overview with thumbnails. Since my case was images with transparency, I wanted to choose the PSD format for the output so that layers are preserved for Photoshop.

So that the layers are also saved in Photoshop format, you have to select the PSD format when saving and then select the "Options" button. In the following window you then put a check mark next to the point "Layers".

In the backup options of the PSD format, you have to check the box next to "Layers" so that they are also saved.

In the backup options of the PSD format, you have to check the box next to "Layers" so that they are also saved.

Small bug: transparent images are reduced to the background level

Unfortunately, there then follows a small bug in GraphicConverter, because even if you have activated the layers in the PSD options, the originally transparent layer is still calculated on a white background in the finished PSD and saved without transparency.

However, I have found a workaround that is still possible: You create another layer via the "Layers" menu and the "New Layer" menu item and drag it to the background. Use the "Window" menu and the "Layers visible" item to open the window in which you can change the order of the layers.

Now you save the file via "File" and "Save as" in the "PSD" format and it works with the transparency channel when you open the image file in Adobe Photoshop.

So that the finished PSD file is actually saved with transparency, you have to create a new layer in the WebP file in GraphicConverter before you save the graphic in PSD format.

Conclusion: GraphicConverter is the Swiss Army Knife for image conversion

If you have to convert graphics in different image formats or work with large amounts of files, edit them, add watermarks or convert the resolution, you will enjoy GraphicConverter.

I got the family license for 5 Macs straight away, which only costs EUR 49,95. The full version for a single user costs only EUR 34,95. You can download the trial version of the software Download here at Lemke Software.

If you still have practical tips on working with WebP files on the Mac, I would be happy to hear your comment.

Do you like my blog? Then I would be happy to receive a short review on Google. Easy leave something here for a moment - that would be great, thank you!


  1. Michael Bach says:

    Yes, GraphicConverter is SUPER, have been using it for around 20 decades.

    "WebPFormat.plugin" does not come from a verified developer ": What _sometimes_ works is the following: immediately after this message appears, go to System Preferences> Security & Privacy> General. The message appears again in the window (maybe :) with a button that you want to trust her. Maybe you are lucky.

  2. math says:

    Pixelmator will open and convert it too!

  3. Gerri says:

    With .webp just make a copy of the image file and change the ending .webp to .jpg.

    • Jens Kleinholz says:

      Hi Gerri! Your suggestion doesn't work for me. When I rename a WebP file and then drag it to Photoshop, I get this message: "Couldn't open“ untitled-2000.jpg ”because an unknown or invalid JPEG marker was found." And opening the WebP file on the Mac in the preview also works without renaming ... only Photoshop is still messing around.

      • Gerri says:

        Hi Jens! It works fine for me (with Windows 10). When testing on the iPad, the file could also be opened (in Keynote). The WEBP file did not appear in the first place (as with Impress and PowerPoint).
        Maybe Photoshop is more "sensitive" ;-)).

        • Jens Kleinholz says:

          Hi Gerri! Ok, I didn't assume that you were talking about Windows, because this post is about the Mac. : D But yes, I also think that Photoshop is a bit peculiar. What I don't understand: WebP wasn't just around yesterday and it is now established on the Internet. Why can't the leading image editing program do that yet ??? Incomprehensible…

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