How Flyingkiwi fits a chat model into a browser tab

Flyingkiwi’s English and Turkish models now run inside the page. Nothing you type is sent to a server: the reply is calculated by your browser, the same way a game or a photo editor runs locally. Here is what that takes.

One download, checked file by file

Your first message downloads the model for the language you chose, about 550 megabytes split into small parts. Each part has a fingerprint (a SHA-256 hash) published in a small manifest; the app refuses any part that does not match. Verified parts go into your browser’s cache, so the next visit can start without downloading again, unless the browser clears its storage.

A model shrunk on purpose

Each model is a 0.6-billion-parameter-class network adapted from Qwen3-0.6B. Two changes make it small enough for a tab. Its vocabulary keeps only the word pieces its language actually uses, and its numbers are stored as 8-bit integers instead of 16-bit floats, which halves the download without a measurable change in its answers. We also tried 4-bit versions, half the size again, but every one we measured answered worse, so the app does not use them. Every layer can look back over the whole conversation: limiting most layers to recent text made long chats worse.

A small engine written in C

The calculation runs in WebAssembly, compiled from about a thousand lines of C written for this model. It uses the processor’s vector instructions, can split the work across several processor cores, and keeps the fixed instructions at the start of every chat pre-computed, so your first reply does not wait for them. Long conversations stay manageable because older text is stored compactly.

Honest about being small

A model this size knows much less than large assistants. Flyingkiwi was trained to answer plainly when it knows, to say when it does not or cannot know, such as today’s news, your own private details or the future, and to correct questions built on a false assumption. It still makes mistakes, so check anything that matters. The technical report lists what was measured, including where it falls short.