Developer builds offline-only whiteboard with strict browser policy blocking all network requests

A developer has launched a whiteboard tool at board.jamuny.com that is deliberately prevented from sending any data off the user's device, enforced via a strict Content-Security-Policy header that blocks all fetch, WebSocket, and related browser requests. The no-network guarantee is verified by an automated Playwright test that fails if any non-asset request is detected during drawing, board switching, or exporting. Because multiplayer collaboration requires a server, the developer chose to forgo it entirely, reasoning that transmitting strokes would defeat the tool's privacy-first purpose. The app is built with Astro serving static HTML and minimal JavaScript islands, keeping transferred script weight around 23KB, with a Lighthouse check that breaks the build if that threshold is exceeded. Several technical challenges were resolved during development, including a canvas rendering bug where rough.js drew rectangle edges as disconnected subpaths, causing visible corner gaps at higher stroke widths, which was fixed by switching Clean mode to native canvas drawing calls.