Convert GIF to PNG — Free, 100% Local

GIF is limited to 256 colors, and its transparency is all-or-nothing, which is why GIF edges so often look jagged. PNG supports full color and smooth alpha transparency, so converting GIF to PNG keeps the transparent background intact and gives you a file that's much easier to edit, cut out or composite later — with none of the white-fill you'd get from converting to JPG.

Note that an animated GIF produces a still image containing only the first frame. Also, conversion doesn't invent color: a picture already quantized to 256 colors in the GIF won't become full-color by saving as PNG. What PNG buys you is no further quality loss from here on, plus better transparency and compatibility.