Polypane

Polypane is a development‑focused web browser that integrates directly into a professional’s workflow. It presents multiple viewports side‑by‑side, allowing developers to see how a page renders across different screen sizes without switching windows. The built‑in accessibility tools surface contrast issues, ARIA errors, and other compliance concerns, helping to ensure that sites meet accessibility standards while they are built.

The browser is positioned as the “missing half” of a web development environment, complementing code editors and other tooling. It targets ambitious developers who need to verify responsive design and accessibility in real time, reducing the need for external testing services or manual resizing. Features such as a brand kit and free online utilities are provided to streamline workflow and maintain visual consistency.

Polypane runs on macOS and is released as a stable product, with regular bug‑fix updates evident in the changelog. Its focus on multi‑viewport previews and integrated accessibility checks distinguishes it from generic browsers used for development.