Whiteboards that run in a browser tab

Short answer

Excalidraw is the one most people want: a hand-drawn whiteboard that installs from the browser, needs no account, and keeps working with the network cut. tldraw covers the same ground with a cleaner line. For interface design rather than sketching, Penpot is the open-source option. Whimsical handles flowcharts and wireframes. All of them open in a tab first — installing just gives them a window and an icon.

The sketching whiteboards

Excalidraw is the default answer, and deservedly. The hand-drawn look does something practical: a diagram that looks provisional invites correction, where a crisp one looks decided. It installs from the browser, asks for no account, and keeps working with no connection once its cache is filled.

tldraw is the closest alternative and also works offline. The line is cleaner and the canvas feels more like a design tool than a napkin, which suits some people better.

Mentioned here: ✏️ Excalidraw, 🖊️ tldraw, ✏️ Penpot

When you want a design tool instead

Penpot is the open-source interface design tool — components, prototypes, real layout. It is a heavier thing than a whiteboard and it wants a connection.

Whimsical sits between the two: flowcharts, wireframes and mind maps, faster than a design tool and more structured than a sketch.

Why the browser suits this job

A whiteboard is the tool you reach for mid-conversation. The gap between wanting one and having one has to be seconds, and a download plus an install plus an account is not seconds.

That is the real argument for the format here, more than the offline capability: the tool is a URL you can send to someone, and they are drawing on it before they would have finished creating an account elsewhere.

Getting a real offline whiteboard

Install it, then open it once while connected and let it load fully. The service worker fills its cache on that first visit — the full sequence is here. Skipping that step is why people conclude offline mode does not work.

Whether a given whiteboard keeps your drawings locally is a separate question from whether it renders offline, and worth checking before a flight. We tested Excalidraw specifically.