Sesame's talking-AI app, explained — and is it worth trying?

If you've tried talking to Siri, Google Assistant or a standard voice assistant and found it stilted or robotic — pausing awkwardly, misunderstanding your tone, or just sounding flat — Sesame is trying to fix exactly that. Here's what its new iPhone app is, how it works, and whether it's actually worth downloading.

Sesame is a US startup co-founded by Brendan Iribe (a co-founder and former CEO of Oculus — the virtual-reality company Meta, formerly Facebook, acquired in 2014) and Ankit Kumar, with other Oculus veterans on the team. That background is relevant because building convincing, low-latency audio experiences is hard: it's the same core challenge as making VR feel immersive. The team has been working on this particular problem for years, not months — and it's well-funded, having raised a $250 million round led by the investment firm Sequoia before the app launched.

Before they launched the app, Sesame published the underlying technology — components of their Conversational Speech Model, including the 1B 'CSM-1B' backbone — as open-source software under a licence that lets anyone inspect and use it (Apache 2.0). That meant developers and researchers could run and test it publicly before any consumer product launched. So when Sesame says its voices sound human, the model behind that claim is out in the open for anyone to check — not a black box you have to take on trust. That's rarer than it sounds in AI.

Most AI voices are built to be accurate and clear. Sesame's is built to be natural. There's a difference. Here's a plain-English breakdown:

The technical name for this is prosody — the music of speech. Sesame built their model specifically around getting prosody right, rather than bolting voice on top of a text-based AI after the fact. That's a real engineering choice that makes a real audible difference.

The app gives you four different AI 'agents' to choose from — Maya, Miles, Simone and Charlie — essentially four distinct voice personalities, each with its own character and its own memory of your past chats. Whether you want something more brisk and professional or warmer and conversational, you can pick. That's a thoughtful design decision: the voice you want while driving is probably not the same one you want while cooking. There's also a clever trick under the hood — instead of going silent while it 'thinks', the AI can run searches while it's still talking and fold the results into what it's saying, so the conversation keeps flowing.

If the idea of chatting with an AI rather than typing appeals to you — while cooking, walking, driving, or just when your hands are busy — Sesame is the best place to try that right now. The voice quality is genuinely impressive, and unlike many early-stage apps, this one has credible engineering behind it. It's available on iPhone in 39 countries as a public preview.

These are the main alternatives most people already have on their phone:

Sesame wins on voice naturalness specifically. If that's what matters to you — having an AI that's genuinely pleasant to talk to — it's the obvious first choice for a try. If you want an AI that can also look up your emails, set calendar reminders, and control your apps, the native options have the advantage.

Where to find it: it's available on the App Store as a public preview. Being a preview means features and availability can change, and the free access may eventually give way to paid tiers — standard practice for early-access launches. Check the listing for current terms before you dive in deeply.