Kyutai — Invincible Voice

Taking a research prototype to a product ready to be demonstrated, released and picked up as open source, in under two months.

Sector
Artificial intelligence · Accessibility
Engagement
Prototype → production
Timeline
November 2025 → January 2026
Expertise
Product design & complex interfaces · Product architecture & engineering

Context

Kyutai is a French artificial intelligence research lab. In late 2025, their teams were working on Invincible Voice, an interface designed to let people who have lost the use of speech — in particular through ALS — communicate more easily with those around them.

By the time Kyutai got in touch, the core of the product already worked. But it was still a prototype: the interface had been built to test usage, and the codebase had to evolve before the project could be released more widely.

Two deadlines overlapped. In the immediate term, several demonstrations were scheduled, and the interface had to feel like a finished product straight away. Beyond that, Invincible Voice was meant to be published as open source: performance, code quality, authentication and the ability for others to pick the project up then mattered just as much as the visible experience.

The purpose of the project mattered to us: putting our product and engineering skills behind a tool meant to make communication more accessible.

Our approach

The first priority was set by the calendar: make the experience presentable without waiting for the full technical rework of the product.

Sylvain therefore proposed a visual redesign within a few days. Valentin implemented it immediately, so that Kyutai could run the scheduled demonstrations on a finished interface.

Once that deadline was secured, we took the codebase further. The goal was no longer only that the product should work, but that it should be publishable, maintainable and reusable by other developers. So we set up an independent repository and reworked the frontend, the backend and the infrastructure around that new goal.

Performance was part of the picture too. The audio streams in particular were reworked to run as streaming rather than prefetch, making the experience noticeably more responsive.

Kyutai prototype
Express UX/UI redesign
Codebase rework
Industrialisation
Project ready to be released

From a research prototype to a product others can pick up

The project is a fair illustration of how we work on an existing prototype: preserve what already validates the usage, then progressively strengthen what now has to last.

What we delivered

Within a few weeks, we delivered a new version of Invincible Voice.

The conversation screen
Before
The prototype conversation screen: the discussion, the vocabulary and the suggested replies all shown at the same level.
After
The same screen after the redesign: the conversation at the centre, the suggested replies within reach, the vocabulary grouped to the side.
This is the screen the conversation happens on: the product does exactly what it did before, but what you have to look at in order to answer is now legible at a glance.
Setting the assistant up
Before
The prototype settings: prompt, keywords, contacts and documents in a single dense window.
After
The settings after the redesign: every setting in its own block, with its actions in the same place.
This is the screen the people around the user work with to fit the assistant to them: the content has not changed, its hierarchy has.

A fully reworked user experience

A complete visual redesign, implemented in time for the first demonstrations.

A new frontend and backend codebase

An independent repository and a rewritten application core, ready for release and for other developers to take over.

A more responsive audio experience

Audio streams moved to streaming, improving the responsiveness of the application.

The pieces a usable product needs

Internationalisation, email and Google authentication, user management and the supporting infrastructure.

The final version of our engagement was delivered in January 2026, less than two months after the first conversation.

The Invincible Voice sign-in screen, with account creation.
Authentication and account management, absent from the prototype, are part of what a product meant to be released has to carry.
See Invincible VoiceSee the open-source project

What Kyutai said

Faced with very tight time constraints, Vezero rose to the challenge brilliantly, combining responsiveness and professionalism. The quality of the UX and the fidelity of the implementation genuinely impressed us, all the more so given the deadlines!

Patrick Pérez — CEO, Kyutai

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