Harness Chat

Hundreds of AI models on your own key — web search, real file downloads, automatic memory, and on-device models that work fully offline.

Harness Chat is a beautifully simple AI chat app where you bring your own key.

The app is free. You pay nobody but the models themselves: paste your OpenRouter API key (two minutes, guided in-app) and chat with hundreds of AI models — DeepSeek, MiniMax, Claude, GPT, Gemini, and more — at raw API prices. No subscription, no markup, no middleman.

NO ACCOUNT NEEDED Signing in with Apple or Google is completely optional — it exists only to sync your chats and memory between your phone and the web/desktop app. Skip it entirely and everything stays on your device: your key, your chats, your business.

PRIVATE BY DESIGN Because you're billed at the API level, your conversations fall under model providers' API data policies — not used to train models, unlike free consumer chatbots. No ads, no tracking, no analytics. If you do sign in, you can export everything we hold — every chat and memory — as one JSON file, anytime.

WHAT IT DOES • Real tools: web search, plus files you can actually download — PDFs, spreadsheets, presentations, even small apps and games • Automatic memory (signed in): it learns your preferences across chats • Optional sync: chats follow you between phone and web when signed in • On-device models: download a small model and chat entirely offline, free • Effort control, live cost tracking, and your context usage at a glance

A free OpenRouter account and API key unlock cloud models; on-device models need nothing at all.