Viewport Relay

Synchronize navigation, scrolling, clicks, and form input across mobile-sized windows.

Viewport Relay is a multi-viewport testing tool for frontend development and responsive QA. Enter a URL and choose iPhone SE, iPhone XR, iPhone 16 Pro, iPhone 16 Pro Max, or a custom size. Each viewport opens in its own Chrome window and is arranged on one display. Use one master window to control the others: • Synchronize navigation and scrolling. • Match clicks by DOM identity, or switch to relative coordinates for Canvas and visual apps. • Optionally synchronize standard text, select, checkbox, and radio controls. Passwords, files, and one-time codes are always excluded. • Choose any combination of device name, resolution, and window role for labels, or hide labels completely. • Clear the URL instantly and reuse up to eight recent URLs stored locally. • Show every generated window to bring the full session back to the front, then reload, pause, resume, arrange, or close the session. • Main controls stay visible in a compact launcher; advanced settings are available inline. All synchronization data is processed locally inside the current browser session. Viewport Relay contains no ads, analytics, account system, or remotely executed code. Single purpose: Synchronize navigation, scrolling, clicks, and user-enabled standard form input across user-selected Chrome windows, and manage those windows for responsive layout comparison.