The trick this tool relies on isn't specific to TikTok at all. It's a basic browser behavior that works on plenty of sites. Most people just never think to try it.
Any image on any webpage can usually be dragged
Most images displayed in a browser, on any site, can be clicked and dragged into a blank browser tab or the desktop. Doing so either opens the image directly or shows its underlying file address, depending on the browser. This isn't a hack. It's a standard feature built into how browsers handle images, meant for things like dragging a photo into an email draft.
Right-click often gets you there faster
On most images, right-clicking and choosing "Copy image address" or "Open image in new tab" does the same thing dragging does, just through a menu instead of a mouse gesture. Some sites disable right-click specifically to discourage this. TikTok's DM interface doesn't block dragging the same way, which is exactly why this trick works there.
Why some sites actively try to stop this
Sites that don't want their images easily copied sometimes use invisible overlays, background images instead of actual img tags, or scripts that intercept right-click and drag events. None of this actually makes an image impossible to save, since the browser still has to download the file to display it. It just adds friction for casual users.
The takeaway
If you've ever wondered whether there's an easier way to save something a website is showing you without a screenshot, dragging or right-clicking the image is usually the first thing worth trying, on TikTok or anywhere else. It won't work everywhere, but it works far more often than people expect.