Synthesia's Syren builds a finished video from a prompt

Synthesia launched Syren in beta on October 9, a tool that builds a finished video from a prompt, a preset or a document, image or video you already have.

The London-based company announced the launch in a blog post by chief technology officer Peter Hill. Syren writes the video as code, then a rendering engine plays it back live, so the video takes shape as it is built, Hill wrote.

A creator can start from a sentence, drop in a branded document, image, video, PowerPoint or YouTube link, and Syren assembles motion graphics, animation, avatars, voiceover, music and b-roll. A new editor inside Syren adds playback, a transcript view and chat-based editing, so changes come from asking rather than starting over.

Synthesia is the London avatar-video platform founded in 2017 and used by over 90% of the Fortune 100, according to Wikipedia. Syren runs on a video rendering engine Synthesia built in house. That engine has been powering motion graphics inside Synthesia since June, and Synthesia's update notes name Motion Graphics as the first capability the model powers.

Videos render in the browser, with nothing to install, and run up to three minutes, horizontal or vertical, the post says. Syren is credit-based, and launch credits let every customer make a first video. Enterprise administrators can switch it off at the organization level.

Syren joins Roleplays, Surveys and the Synthesia editor on the platform. It is not Synthesia's first agentic product: the company launched Sessions, a platform for two-way conversations with avatars, on October 1. The editor stays the place for content that has to be exact and repeatable, including compliance training and onboarding.

Hill described Syren as "a creation experience where the AI agent doesn't assist the editor, it is the editor." Chief executive Victor Riparbelli wrote on LinkedIn that Syren is "now live and FREE to try," and that it runs in the browser or through a Claude connector.

Syren will soon learn a company's brand from its existing videos, matching graphics, motion style, pacing and the rhythm of its edits, the post says.

Syren is available in beta to self-serve, free and all Enterprise customers, through a Syren button in the left-hand navigation of Synthesia.