I built a local LLM that runs entirely in your browser. No install, no GPU, no server

A few months ago I got obsessed with a question: can you run a real LLM entirely inside a browser tab, with zero backend, zero GPU, and zero install?

The answer is yes. Here's what I built.

ghost is a single HTML file that downloads a quantized language model into your browser's cache on first visit, then runs inference locally in WebAssembly forever after. Fully offline after that first download. No API key. No npm. No build step. Open the file, pick a model, chat.

How it works

The inference engine is wllama — a WebAssembly binding for llama.cpp. It runs GGUF quantized models directly in the browser using WASM SIMD. I pin it to a specific version so the JS and WASM files always match (learned this the hard way after a fun debugging session involving mismatched memory imports).