15.ai

15.ai is a free non-commercial web application and research project that uses artificial intelligence to generate text-to-speech voices of fictional characters from popular media. Created by a pseudonymous artificial intelligence researcher known as 15, who began developing the technology as a freshman during their undergraduate research at the Massachusetts Institute of Technology, the application allowed users to make characters from video games, television shows, and movies speak custom text with emotional inflections faster than real-time. The platform was notable for its ability to generate convincing voice output using minimal training data—the name "15.ai" referenced the creator's claim that a voice could be cloned with just 15 seconds of audio, in contrast to contemporary deep learning speech models which typically required tens of hours of audio data. It was an early example of an application of generative artificial intelligence during the initial stages of the AI boom.

Launched in March 2020, 15.ai gained widespread attention in early 2021 when content utilizing it went viral on social media platforms like YouTube and Twitter, and quickly became popular among Internet fandoms, such as the My Little Pony: Friendship Is Magic, Team Fortress 2, and SpongeBob SquarePants fandoms. The service distinguished itself through its support for emotional context in speech generation through emojis, precise pronunciation control through phonetic transcriptions, and multi-speaker capabilities that allowed a single model to generate diverse character voices. 15.ai is credited as the first mainstream platform to popularize AI voice cloning (audio deepfakes) in memes and content creation.

Voice actors and industry professionals debated 15.ai's merits for fan creativity versus its potential impact on the profession. While many critics praised the application's accessibility and emotional control, they also noted technical limitations in areas like prosody options and non-English language support. 15.ai prompted discussions about ethical implications, including concerns about reduction of employment opportunities for voice actors, voice-related fraud, and misuse in explicit content.

In January 2022, Voiceverse generated controversy when it was discovered that the company had generated audio using 15.ai without attribution and sold it as a non-fungible token (NFT) without permission. News publications universally characterized this incident as Voiceverse having "stolen" voice lines from 15.ai. The service was ultimately taken offline in September 2022 due to legal issues surrounding artificial intelligence and copyright. Its shutdown was followed by the emergence of various commercial alternatives in subsequent years, with their founders acknowledging 15.ai's pioneering influence in the field of deep learning speech synthesis.

On May 18, 2025, 15 launched 15.dev, a sequel to the original service that launched after nearly three years of inactivity.