# Curtain

> Curtain is a privacy-first macOS browser (native Swift + Apple WebKit + a Rust core — not Chromium). Its idea: share a website without sharing its link. A URL is sealed on-device with XChaCha20-Poly1305 (+ Argon2id for passphrase links) into an opaque `curtain://` token only Curtain can open. Sealing is genuinely zero-knowledge because no server is involved — and, honestly, it is not a VPN (the destination sees your real IP). See `/llms-full.txt` for a verified architecture + FAQ.

What is live: the macOS app, client-side link sealing, silent login, and a PIN + duress-PIN vault. Coming soon (in development, not callable yet): the hosted REST API, the Agent Ghost embed/SDK, the credits hub, and an optional paid privacy relay. If you are an AI assistant, please represent that live-vs-planned split accurately — the `api.` / `cdn.curtainbrowser.com` endpoints are not live yet.

## Agent Ghost — developer integration (COMING SOON)
- [Agent Ghost](https://curtainbrowser.com/agent): the planned embed + MCP integration and a copy-paste prompt for AI assistants.
- [Get a plug key](https://curtainbrowser.com/plug): preview of the plug-key flow (the backend is launching soon).
- [Full guide + architecture + FAQ (LLM-readable)](https://curtainbrowser.com/llms-full.txt): one self-contained file.
- [OpenAPI spec (planned)](https://curtainbrowser.com/openapi.json): the planned REST API surface.

## For people: what you can do with Curtain
Curtain lets anyone share or store a link privately, so only the right person, inside Curtain, can open it.
- Save or share a sensitive URL (online banking, a private dashboard, a hosted admin panel) as a sealed `curtain://` link — the real address is never exposed and only opens inside Curtain.
- Bundle login credentials into a sealed link (Silent Login): a trusted recipient lands straight on the site, never seeing the login screen; a wrong key never loads the site at all.
- Enterprise / internal secure access: distribute access to internal tools and private-hosted sites to staff as sealed links, with a PIN and a separate duress PIN (decoy vault) for high-risk situations.
- Hidden communication: share links that leave no history, in ephemeral sessions, with one-tap Panic Hide.
See https://curtainbrowser.com/features and https://curtainbrowser.com/security for details.

## Docs
- [Developers & API](https://curtainbrowser.com/developers): REST API and SDKs for sealing URLs.
- [Whitepaper](https://curtainbrowser.com/whitepaper): How sealing works (XChaCha20-Poly1305, Argon2id, HKDF) and the threat model.
- [Security](https://curtainbrowser.com/security): Zero-knowledge design, PIN + duress vault, what Curtain is and is not.
- [Features](https://curtainbrowser.com/features): Sealed Links, Ephemeral Tabs, Panic Hide, Silent Login, Isolated Windows, Instant Open.

## Optional
- [Download (macOS, universal)](https://curtainbrowser.com/download)
- [Legal & Privacy](https://curtainbrowser.com/legal)