node‑png is a native Node.js addon (written in C++) that uses libpng to encode raw RGB(A) or grayscale buffers into PNG images entirely in memory. It provides a simple `Png` class for single‑image encoding and two stacking utilities—`FixedPngStack` for compositing images onto a fixed‑size canvas and `DynamicPngStack` for automatically sizing the canvas to fit a set of positioned images—targeted at developers who need fast, low‑level PNG generation within Node applications.