Before Applitools Visual Grid, visual UI tests were run serially. Each page was checked, one by one. For each page, a screenshot was taken using the automation framework. Then the screenshot was uploaded to Applitools, analyzed, and based on the result, either failed the test or kept it running.
Checking each page might take a couple of seconds. Doesn’t sound like much, but when hundreds of screenshots are multiplied across multiple viewport sizes and browsers, those seconds add up.
Applitools Visual Grid eliminates this bottleneck. Your visual tests go 30x faster. Here’s how.
Applitools SDKs upload DOM Snapshots — not screenshots — to Applitools Visual Grid. DOM Snapshots fully describe the HTML, images, CSS, fonts, and other resources needed to render a page. DOM Snapshots are smaller than screenshots, so they can be uploaded faster.
Applitools Visual Grid does not always upload all elements of the DOM Snapshot for every page. Instead, it saves DOM Snapshot elements from one test to another. If any elements — HTML, CSS, SVGs, fonts, or other resources — are unchanged, it doesn’t upload them. Since most of these resources don’t change from one test run to another, there’s less to transfer, and upload times are measured in milliseconds.
Applitools Visual Grid runs screenshot jobs in parallel by farming them out to a grid of hundreds of browsers in the cloud that generate screenshots of web pages for all the different combinations of browser types, viewport sizes, and emulated devices you request. This lets you test responsive web pages and components on a range of page widths corresponding to phones, tablets, laptops, and external monitors.