A high-performance, lightweight, and completely free screen annotation tool built specifically and optimized for Windows 11.
"While taking my NIELIT 'O Level' course, I found myself in need of a good screen annotation tool. However, I quickly realized that most existing options were either locked behind paywalls, bloated with unnecessary features, or suffered from laggy, outdated user interfaces.
Frustrated by these limitations, I decided to build my own solution using AI. The result is Pen 11—a blazing-fast, highly responsive, and meticulously optimized screen marker that respects your system's resources. It is entirely free and open-source, allowing anyone in the community to use it, learn from it, or modify it to suit their own needs."
- Smooth Toolbar Collapse / Expand: When ink is hidden (or toggled via
Ctrl+5), the toolbar collapses into a clean, minimal floating pill containing only the unhide button (🙈) and drag handle usingQPropertyAnimationwith cubic easing curves (InOutCubic,240ms). Expanding back restores full height with zero visual jumps or layout fighting. - Non-Blocking Opacity Transitions: Floating sub-toolbars (Color Palette, Shapes Menu, Cursor Options) fade in and out using
InOutSineeasing (150ms/120ms). The animation dynamically reverses from the current opacity when toggled rapidly, completely eliminating snapping or flickering.
- Truly Independent Panels: Color Palette, Shapes Menu, and Cursor Toolbars function as modular floating panels. Clicking the main toolbar surface will never close or reset your sub-toolbars.
- Intelligent Drag Synchronization: When dragging the main toolbar, attached sub-toolbars glide smoothly along with it without restarting animations. Once you independently drag a sub-toolbar to a custom screen position, it remembers its exact coordinates and stays anchored where you placed it.
- Auto-Dismiss on Tool Switching: Selecting a drawing tool (Pen, Highlighter, Eraser) cleanly dismisses temporary popups while keeping your Color Palette open for continuous work.
- Native Mouse Tracking & Hover Detection: Sub-toolbar buttons instantly update to
PointingHandCursorand display crisp tooltips on hover without stealing window focus from your target applications (Word, browsers, presentations). - Multi-Click Responsiveness: Rapidly clicking across color swatches or tool options remains 100% fluid with no cursor lockup or event dropping.
- Oriented Bounding Box (OBB) Engine: Selected strokes and shapes track their exact oriented geometry during rotation, dragging, and scaling.
- Collision-Resistant Transform Handles: Handle physics (Rotate, Delete, Scale) dynamically adjust spacing to prevent overlap on thin or elongated shapes.
- Float-Precision Scaling: Scaling objects maintains correct relative stroke widths without nib distortion.
- Gesture-Based Geometric Detection: Hold your pen for
400msat the end of a drawing stroke to automatically snap into perfect lines, circles, or ellipses.
- Built-in Storage Manager: Automatically saves your custom pen/highlighter/eraser sizes, active colors, shape preferences, and toolbar screen coordinates to disk across sessions.
- Single-Instance IPC Guard: Inter-process communication via
QLocalServer/QLocalSocketguarantees that only one instance of Pen 11 runs at a time, eliminating hotkey conflicts and duplicate processes. - Infinite Drawing & OOM Protection: Handles up to
50,000simultaneous strokes on screen with a massive5,000-step Undo stack.
Pen 11 is ultra-lightweight, uses almost 0% CPU when idle, and takes less than 50 MB RAM.
- OS: Windows 10 or Windows 11 (Best experience on Windows 11 / 11 Pro)
- RAM: 50 MB to 100 MB free memory
- Graphics: Any basic GPU supporting DirectX 11 (Intel, AMD, NVIDIA)
- Storage: 40 MB free disk space (Portable
.exe— no installation needed) - Display: Works on all screen resolutions (720p, 1080p, 2K, 4K) & high refresh rates (60Hz, 120Hz, 144Hz+)
💡 Why it runs so smoothly: Pen 11 uses GPU acceleration (Direct3D 11), high process priority, and 1ms timer precision to deliver a 100% lag-free drawing experience on Windows.
- Download: Grab the latest
Pen 11.exefrom the Releases page. - Run Portable: No installer required! Simply double-click to launch.
- The Main Toolbar: Appears at the top-right of your screen. Drag it anywhere by its top pill handle or background.
- Drawing Tools: Click Pen (
Ctrl+1), Highlighter (Ctrl+2), or Eraser (Ctrl+3). Long-press any tool button to open the instant line size selector. - Shapes Sub-Menu: Click the Shape button (
📐) to open the geometric palette (Line, Arrow, Rectangle, Rounded Rectangle, Circle, Triangle). HoldShiftwhile drawing for 1:1 square/circle aspect ratios or 45° angle snapping. - Colors Palette: Click
🎨(Ctrl+P) to toggle the 12-color floating palette. Drag it anywhere on screen. - Selection / Lasso Mode: Click
↖️or pressCtrl+4. Click an object or draw a lasso circle around multiple strokes to move, rotate, scale, or delete them. - System Tray: Minimizes to the Windows System Tray with quick access to About, Clear Screen, and Exit.
| Shortcut | Action |
|---|---|
Ctrl + 1 |
Select Pen Tool |
Ctrl + 2 |
Select Highlighter Tool |
Ctrl + 3 |
Select Eraser Tool |
Ctrl + 4 |
Select Cursor / Selection Mode (Lasso & Transform) |
Ctrl + 5 |
Toggle Ink Visibility (Collapses/Expands Toolbar) |
Ctrl + Z |
Undo last stroke |
Ctrl + Shift + C |
Clear Screen |
Ctrl + ] |
Increase Tool Size |
Ctrl + [ |
Decrease Tool Size |
Ctrl + P |
Toggle Color Palette |
Ctrl + B |
Toggle Whiteboard / Blackboard / Transparent Mode |
Ctrl + Q |
Exit Application |
Delete / Backspace |
Delete selected shape (in Selection Mode) |
Shift + Draw |
Snap to regular aspect ratio / 45° line angles |
# 1. Clone the repository
git clone https://github.com/Narayan6204/Pen-11.git
cd "Pen-11"
# 2. Install dependencies
pip install -r requirements.txt
# 3. Run the app
python main.pypython -m PyInstaller main.spec --noconfirmThe compiled binary will be placed directly in the dist/ directory as Pen 11.exe.
If you find Pen 11 helpful for your studies, teaching, or daily workflow and want to support its continued development, you can buy me a coffee by scanning the UPI QR code below!
UPI ID: narayanadev@ptyes
Released under the MIT License.
Developed with ♥ by Narayan Dev.