Sesame, the conversational AI startup co-founded by former Oculus CEO Brendan Iribe and Ankit Kumar, has launched a public iOS preview of its personal agents app. The app puts four named AI characters , Maya, Miles, Simone, and Charlie , in your pocket, each with a distinct voice, personality, and persistent memory. The pitch is simple but technically ambitious: voice-first AI that actually feels like a conversation, not a command prompt.

From a viral demo to a real app

Sesame's story started with a splash. The startup first emerged from stealth offering two demos of its technology , AI voices named Maya and Miles , which were accessed by more than a million people within the first few weeks. That wave of interest helped Sesame close a serious funding round: the company raised a $250 million Series B , with investors including Sequoia, Spark, and other undisclosed backers.

The Research Preview that followed was invite-only and web-based. This iOS launch is the first time the general public can download and use Sesame without waiting for a special invite , though access is free during the preview phase, with potential waitlisting to ensure quality.

The hard problem: thinking while talking

Most voice AI today works in a serial pipeline: listen, think, then speak. That creates an awkward pause that breaks the illusion of real conversation. Sesame's core technical bet is that you have to do all three simultaneously.

There's an inherent tension between replying quickly and taking the time to compose thoughtful responses. A slower response is usually more correct, but it can also feel unnatural if it takes too long. Sesame's answer is a custom architecture called the Conversational Speech Model (CSM). Unlike traditional text-to-speech pipelines that first generate text and then synthesize audio, CSM is end-to-end and multimodal , it processes text and audio context together in a single model, which allows the AI to "think" as it speaks, producing not just words but also the subtle vocal behaviors that convey meaning and emotion.