Once the pandemic normalized virtual meetups, the concept of “personalized AI” began to gain steam.

Startups creating “AI-driven” avatars — realistic-looking characters with synthetic voices that star in pre-recorded or live videos — have raised hundreds of millions of dollars in venture capital over the past few years. As such avatars improve, they promise to deliver more personalized digital marketing and training experiences while reducing the costs typically associated with video production.

That’s at least the sales pitch from Synthesia, one of the startups using AI to create synthetic videos for advertising and other use cases. The company yesterday announced that it raised $90 million in a Series C round led by Accel with a strategic investment from Nvidia and participation from Kleiner Perkins, GV, Firstmark Capital and MMC. The round brings Synthesia’s total raised to date to $156.6 million, and it values the startup at $1 billion post-money (up from $300 million in December 2021).

Co-founder and CEO Victor Riparbelli tells TechCrunch that Synthesia is a “sustainable business” and wasn’t looking for an additional investment, but that Accel and Nvidia approached the company with a compelling offer.

“We now have over 50,000 customers,” Riparbelli said via email. “We don’t disclose revenue figures at this time, but the company has a year-over-year user growth rate of 456% and over 15 million videos generated on the platform to date.”

Founded in 2017 by a team of AI researchers and entrepreneurs from University College London, Stanford, Technical University of Munich and Cambridge, Synthesia, which now employs around 200 people, is developing AI tech that lets customers create instructional videos featuring stock or custom AI avatars. Users type in text, select an avatar and choose a language to generate videos.

Image Credits: Synthesia

Synthesia’s AI is trained on real actors, and actors are paid per video that’s generated with their image and voice.

Among Snythesia’s clients are Tiffany’s, IHG, Teleperformance, BSH, Moody’s Analytics and entities of the United Nations. According to Riparbelli, 35% of the Fortune 500 is using the startup’s for training and marketing purposes

“Synthesia is transforming physical video production into an entirely digital process that will enable creators to bring their ideas … to life with just a Synthesia account,” Riparbelli said. “Our mission is to make video easy for everyone.”

Some experts have expressed concern that tools like Synthesia’s could be used to create deepfakes, or AI-generated videos that take a person in an existing video and replace them with someone else’s likeness. The fear is that these fakes might be used to do things like sway opinion during an election or implicate a person in a crime.

In a piece for The Wall Street Journal, columnist Joanna Stern found that the likeness she created with Synthesia could fool her family and nearly tricked her bank. Tech developed by Synthesia has also been misused to produce propaganda in Venezuela and false news reports promoted by pro-China social media accounts.

Synthesia, for its part, says that it vets its customers and their scripts and requires formal consent from a person before it’ll synthesize their appearance. Its four-person disinformation team suspends accounts found to have violated its terms of service, which prohibit the use of its tech for “political, sexual, personal, criminal and discriminatory content.”

Riparbelli says that the investment from the Series C will be put toward making Synthesia’s avatars more expressive and the Synthesia platform faster and “more collaborative.”