IE NetRenderer vs Web Platform Tests

IE NetRenderer is a free web service and extension for checking how pages render in Internet Explorer 11, 10, 9, 8, 7, 6 and 5.5. It runs capture jobs in parallel and in real time, using a separate virtual Windows environment for each browser version. Mixed Overlay and Difference Mode compare screenshots between versions. Screenshots remain at their original size, with a ruler showing usable widths for 800x600 and 1024x768 displays. You can set a vertical pixel offset to capture a lower page section and optionally allow extra loading time for scripts and page objects. Java and ActiveX are blocked, while JavaScript is enabled. The Firefox extension sends the current page from browser menus or toolbar icons. The maker says images and URLs are private, images are deleted after viewing, and visited sites do not receive identifying browser details. The rendering server is in Germany.

Web Platform Tests is an open-source suite for checking web platform compatibility across browser implementations. Anyone can run tests through the public wpt.live deployment in an internet-enabled browser, or clone the suite for local use on Linux, macOS, or Windows. The suite includes JavaScript API, rendering, crash, WebDriver, and manual tests. Its command-line `wpt` tool runs tests in a selected browser and can produce machine-readable JSON reports and screenshots. It can also save and load expected results for continuous integration and regression tracking. Regularly collected results from a range of browsers are archived at wpt.fyi. Local setup requires Python 3.9 or later and configuration of test domains in the system hosts file. Running tests in multiple browser processes may make results less deterministic and add noise compared with the default single-process mode. The project is free and open source, and documents Windows, macOS, and Linux setup.