Cipher

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A stealth desktop overlay for private screen capture and AI chat. Hidden from Zoom, Teams, OBS, and most screen recorders. OCR runs on your machine. Only text goes to your AI provider.

Why Cipher?

You want answers from what's on your screen without broadcasting your overlay to everyone on a call or recording.

Cipher sits on top of your desktop, captures what you need, reads the text locally, and talks to OpenAI, Claude, Gemini, or Grok. One chat-style flow. One input box. Captures show up on your side like a normal conversation.

Table of Contents

Click to expand

• Features
• Getting Started
  • Download
  • Run from Source
  • Build
• Usage
  • Settings
  • Chat Flow
  • Hotkeys
• Development
  • Tech Stack
  • Project Layout
• Support
• Disclaimer
• License

Features

• Stealth overlay — hidden from taskbar, Alt+Tab, and Windows screen capture APIs used by Zoom, Teams, OBS, and similar tools.
• Silent capture — no snipping tool popup. Cipher steps aside for a split second and grabs what's behind it.
• Chat-style UI — capture screens, they appear on your side of the thread. Type and hit Send.
• Multi-screen support — stack several captures for long pages or multi-part questions.
• Local OCR — Tesseract extracts text on your PC. Images are not sent to the AI.
• Rich replies — markdown and fenced code blocks render cleanly in the chat.
• Provider choice — OpenAI, Claude, Google Gemini, and Grok (xAI) with a model picker.
• Encrypted keys — API keys stored with the OS keychain (DPAPI on Windows, safeStorage elsewhere).

Getting Started

Download

Grab the latest build for your OS from the continuous release (updated on every push to main).

Platform	File
Windows (x64)	Cipher.exe — portable, no installer
macOS (Apple Silicon)	Cipher-mac-arm64.dmg
macOS (Intel)	Cipher-mac-x64.dmg
Linux (x64)	Cipher-linux.AppImage

Run the app, add your API key in Settings, and you are good to go.

macOS: Open the .dmg, drag Cipher to Applications, then right-click → Open the first time (unsigned app).

Linux: chmod +x Cipher-linux.AppImage then run it. AppImage needs FUSE on some distros (libfuse2).

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Run from Source

Requirements

• Node.js 18 or newer
• Windows, macOS, or Linux

Install and launch

git clone https://github.com/false200/Cipher.git
cd Cipher
npm install
npm start

Cipher opens as a floating overlay on your desktop.

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Build

npm run build        # Windows x64 → dist/Cipher.exe
npm run build:win    # same as above
npm run build:mac    # macOS dmg (x64 + arm64) → dist/Cipher-mac-*.dmg
npm run build:linux  # Linux AppImage → dist/Cipher-linux.AppImage

Every push to main triggers a GitHub Actions matrix build for all three platforms. Artifacts land on the continuous release.

Usage

Settings

1. Open the Settings tab
2. Pick your provider (OpenAI, Claude, Gemini, or Grok)
3. Choose a model
4. Paste your API key and click Save

Keys stay encrypted on your device.

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Chat Flow

1. Open Assistant
2. Click Capture or press Ctrl+Shift+C — the screen shows on your side of the chat
3. Capture again to stack more screens (scroll down first, then capture the next part)
4. Paste an image with Ctrl+V if you prefer
5. Type your question in the box at the bottom (optional — Send works with captures alone)
6. Hit Send or press Enter
7. Cipher reads the screen locally, asks your model, and replies in the thread
8. Keep the conversation going in the same input box

To quit, use the X in the title bar. That is the only way to close Cipher.

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Hotkeys

Key	Action
`Ctrl+``	Show or hide Cipher
Ctrl+Shift+C	Capture the screen
Ctrl+V	Paste an image into the capture stack
Enter	Send message

Development

Tech Stack

Layer	Tech
Desktop shell	Electron 28
Packaging	electron-builder
OCR	Tesseract.js
AI	OpenAI-compatible APIs, Anthropic, Google Gemini

Project Layout

Path	Role
index.html	Chat UI, settings, markdown rendering
main.js	Window, stealth mode, IPC, hotkeys
preload.cjs	Secure bridge between UI and main process
ai/capture.js	Stealth screen capture
ai/ocr.js	Local text extraction
ai/providers.js	Provider adapters
ai/settings.js	Encrypted key storage
ai/system-prompt.js	Shared assistant instructions
ui/markdown.js	Code block and markdown rendering
.github/workflows/build.yml	CI matrix build + continuous release (Win / Mac / Linux)

Support

If Cipher helped you, star this repo so others can find it.

Disclaimer

Cipher uses OS-level content protection. It works against software screen capture (Zoom, Teams, OBS, Game Bar, and similar tools).

Hardware capture through an HDMI capture card cannot be blocked in software.

You are responsible for how you use this tool and for complying with the terms of your AI providers and any platform you are on.

Use at your own risk.

License

MIT

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