Online Sketchpad

Worked example: the undo limit and brush size range

The canvas is internally fixed at 960 by 560 pixels. Regardless of how wide it displays on screen, mouse or touch coordinates are converted back to this fixed size, so a line drawn on a small phone screen maps to the same internal coordinates as one drawn on a large desktop screen, and the exported PNG is always 960 by 560.

Undo remembers at most 30 steps: after every completed stroke, the tool saves the whole canvas as a PNG snapshot in its history. Past 30 snapshots, the oldest one is dropped, meaning clicking "Undo" more than 30 times in a row can no longer bring back the earliest strokes.

• The brush-size slider ranges from 1 to 48 pixels, with a live readout next to it such as "8 px".
• Undo tracks the "most recent 30 canvas snapshots," not the "most recent 30 pointer movements."

How to verify before exporting, and the split with Flowchart Maker

To verify before exporting, click "Export PNG," reopen the downloaded image, and confirm the stroke position, color, and thickness match what was on screen. If the drawing needs to sit on a colored background later, note that this tool cannot output a transparent background, so a separate background-removal step is needed.

If what is needed is a diagram with directional arrows and double-click-editable text rather than freehand drawing, this site's Flowchart Maker offers draggable rectangle and diamond nodes. Both export PNG, but sketchpad strokes are not objects — once drawn, they are plain pixels with no way to edit the text or position of a single stroke afterward.

How to use

1. Pick a brush color and adjust the brush size.
2. Draw on the white canvas with a mouse, trackpad, finger, or stylus.
3. Turn on the eraser when needed, and use undo to remove the previous stroke.
4. Export PNG to download the current canvas.

Use cases

• Make quick sketches, signatures, annotations, classroom whiteboard notes, or sticker ideas.
• Capture simple shapes and thoughts from a phone or tablet.
• Export a PNG for documents, slides, chat, or notes.

Who is it for

• Users who need a quick freehand sketch, signature, or annotation
• Teachers creating classroom whiteboard-style diagrams
• Users capturing quick ideas from a phone or tablet

Real examples

Good to know

• Undo history keeps at most 30 steps; beyond that, the oldest strokes can no longer be undone and only "Clear" starts over.
• The eraser paints white over strokes rather than clearing to transparency; the exported PNG always has an opaque white background.
• There are no objects or layers here — once drawn, it is a flat pixel image, and no individual stroke can be moved afterward.