ByteDance has developed a deepfake face swapping feature for TikTok, but hasn't released it

Functionality for the unreleased Face Swap feature in Duoyin, TikTok's Chinese sister app. (TechCrunch)

An Israeli research startup reportedly found code in TikTok and its Chinese sister app Duoyin for a feature called "Face Swap," which allows users to plant their face on videos of other people.

The startup, Watchful.ai, shared the news with TechCrunch, who first reported on it earlier this month.

Watchful.ai was able to activate the code and see how it works. The app goes through several checks to make sure its scanning a real person and not a photo -- it asks you to blink, open and close your mouth, and so on.

According to the features terms of service (which Watchful.ai found in both Duoyin and in English in TikTok), only users 18 and older will be able to use it, if it ever gets an official release.

But in theory, if you pass all those criteria, you can put your face on someone else's body:

You’ll then be able to pick from videos ByteDance claims to have the rights to use, and it will replace with your own the face of whomever is in the clip. You can then share or download the deepfake video, though it will include an overlayed watermark the company claims will help distinguish the content as not being real. I received confidential access to videos made by Watchful using the feature, and the face swapping is quite seamless. The motion tracking, expressions and color blending all look very convincing.

TechCrunch reached out to TikTok in the US, where a spokesperson denied that the feature was slated for release on the immensely popular app.

"This is definitely not a function in TikTok, nor do we have any intention of introducing it," a TikTok spokesperson wrote. "I think what you may be looking at is something slated for Douyin."

Watchful.ai found the code functionality and terms of service inside TikTok, however.

When TechCrunch reached out to Duoyin, the answer was more curt:

"Douyin follows the laws and regulations of the jurisdictions in which it operates, which is China," the spokesperson said.

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