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In this section you’ll find helpful engineering guides and standards that have been produced by the PIE team.

Browser support

Users have access to hundreds of versions of browsers, so instead of assessing them all individually we've come up with a rating system which defines different levels of browser support and the testing requirements for each level. We've assigned the highest ratings to the browsers that are most commonly used by our customers.

Priority definitions

Priority level A = Fully supported

  • Testing is required
  • All content must be available
  • Layout must comply with the design, unless technical needs prevent this
  • All functionality must be available and work as required

Priority level B = Mostly supported

  • Testing is required
  • User should be able to place an order or carry out the main function of the page
  • Layout doesn't have to be identical to the design, but should retain its functionality

Priority level C = Not supported

  • Testing is not required

A good example of this would be users browsing using Opera. The reason we don't "Fully Support" this browser is simply down to user metrics, not the quality of the browser. We'd actually expect most functionality to work with no real issues, although we don't officially test in this browser.

Browsers and their ratings


Browser Grading
Chrome, last 3 versions (MacOS & Windows) A
Edge, last 3 versions (Windows) A
Firefox, last 3 versions (MacOS & Windows) A
Safari (MacOS), last 3 versions A
All other browsers & versions C


Browser Grading
Safari (iPhone), last 3 versions A
Safari (iPad), last 3 versions A
Chrome (Mobile), last 3 versions A
Samsung Internet, last 3 versions B
All other browsers & versions C


To give an idea as to what devices are worth testing on, these are the current recommended device types based on our analytics.

Device Models
iPhone 6 to latest (all variants such as Pro and Mini)
iPad / iPad mini Latest model
Samsung Galaxy S21, S22
Samsung Galaxy Tab S7 to latest
Google Pixel 4a, 6
Huawei P30