OpenPnt from PXStudio is a lightweight, open-source screen annotation tool built for Windows, designed to add visual marks during live demos and remote presentations. The app draws directly over active windows in real time, letting presenters highlight areas without changing the underlying application. It provides pen options, basic shape drawing, and an immediate clear command for temporary marks. Educators and technical presenters benefit from a distraction-minimizing overlay that keeps audience focus on the display.

OpenPnt runs as a portable, single-file overlay

The app ships as a standalone executable that can be launched from a USB drive or cloud folder, so administrators do not need to run a setup wizard. That portability suits ad-hoc teaching setups and on-site demos where installation is restricted. Because it targets the Windows desktop environment specifically, it attaches to the active window or desktop without altering system settings.

It keeps CPU and memory usage very low during presentations

PXStudio describes the tool as having an extremely low system resource footprint, which means the overlay runs without noticeable lag on typical presentation hardware. The app draws only on the display layer rather than processing the underlying application, so background CPU and RAM consumption remains small during real-time annotation, allowing video playback or conferencing software to continue without interruption in most cases.

The overlay behaves safely but has limits with some full-screen apps

Open-source design and single-file distribution reduce the need for elevated permissions, and the drawing layer does not write to system files by default. Some exclusive full-screen applications that use certain graphics modes can prevent the overlay from appearing, so annotations may disappear during particular games or video players. For a permanent record of marks, capture the screen with a standard screenshot tool while annotations are visible.

Minimal controls make it accessible, but advanced editing is absent

The interface concentrates on essential marking tools and global keyboard shortcuts, which keeps the learning curve short for educators and presenters. Users who need layered edits, timed playback of annotations, or native export of drawings must look elsewhere. That focus aligns with the developer's intent to avoid heavy graphical complexity, making the app best suited to quick guidance rather than detailed illustration work.

A practical, focused tool for presenters

The app is a pragmatic option for presenters and educators who need transient, in-session visual guidance rather than exported assets. Its narrow scope reduces setup friction and keeps interactions uncomplicated. Users requiring detailed exports or layered editing should consider a different tool. On balance, the app delivers reliable, low-overhead annotation for quick demonstrations and classroom use. Check overlay visibility before each session to avoid surprises. Recommended.