lightweight

A lightning fast, native macOS chat app for OpenRouter. 2 MB download. ≈35 MB idle memory.

Lightweight running with its powder blue theme
Lightweight running with its dark theme

MIT licensed.

You’ll need an OpenRouter API key.

FAQs

Is this secure?
Your API key is kept in macOS Keychain. Chat requests go directly from your Mac to OpenRouter over HTTPS, then to your chosen model provider. The app is open source. Your chats are subject to OpenRouter’s privacy policy and the provider’s policies, but we don't store prompts or replies and the app does not send any analytics or data back to us at all.
Does anything get stored?
Lightweight doesn’t save chat history or log conversations to disk. Each window has its own temporary chat, which disappears when you close it. Your system prompt, custom models, appearance preferences, and cached model list stay on your Mac.
How are models managed?
The app ships with a curated model list and checks GitHub for updates at most once a day. It keeps the last valid list for when you’re offline. You can also add your own OpenRouter model IDs in Settings.
Does this app 'phone home' at all?
No. It makes just two types of outbound request. To OpenRouter and, once a day, fetches an updated model listing file from our GitHub repo (for which we get no analytics or information at all – we don't even know how many people are running the tool).