Rollpie Floor Plan is a free floor plan maker that runs in your browser with no install. Pick a room type and drag on the canvas to draw a room that snaps to the grid. Drag with the wheel button to pan the view.
Click a room to select it, drag to move it, and resize it with the corner and edge handles. Shift-click to add rooms to the selection and merge them, or right-click for the delete and split menu. To place doors and windows, switch the Tool panel to Door or Window and click a wall; drag an end to change the width, and right-click to flip the swing or hinge.
The Size panel edits dimensions in grid tiles, the Grid Precision panel changes how finely everything snaps, and the Wall panel sets the wall thickness. Ctrl+Z / Ctrl+Shift+Z undo and redo, Delete removes the selection, Esc deselects, and Export in the Actions panel saves the finished plan as a PNG.
Double-click a panel title to switch how the panels are laid out. In the movable layout you drag panels wherever you like and keep several open at once; in the fixed layout a single panel sits in the top right.