Blog
Notes from the mosaic.
Responsive-testing techniques and the engineering behind live device viewports. Free is £0; Pro is £12/mo.
2026-07-18 · 5 min read
How to test responsive design on every screen size at once
Stop resizing DevTools one preset at a time. See phones, tablets and desktops render your site simultaneously. Live, interactive, and in sync.
2026-07-18 · 7 min read
How Tessera streams live browser viewports to an infinite canvas
The engineering behind live device tiles: CDP screencast over WebSocket, binary JPEG frames, offscreen pausing, and an SSRF-safe proxy.