Interop 2022 Addresses Browser Compatibility Issues
Written by Ian Elliot   
Wednesday, 09 March 2022

Google, Microsoft, Mozilla and Apple are jointly involved in Interop 2022, a cross-browser initiative to find and address the most important interoperability pain points on the web platform. The end result is a public metric that will assess progress toward fixing these interoperability issues.

Browser compatibility - or rather the incompatibilities between browsers has been a continuing pain point for web developers - but perhaps there's now a real prospect that this headache can be cured with a joint effort towards browser interoperability that will improve the experience of developing for the web, dubbed Interop 2022, being made by Apple, Bocoup, Google, Igalia, Microsoft, and Mozilla.

According to Google:

For the first time ever, all major browser vendors, and other stakeholders, have come together to solve the top browsers compatibility issues identified by web developers.

Interop 2022 is the culmination of an effort that started in 2019 when, in order to identify the problems faced by developers Mozilla conducted MDN Developer Needs Assessment surveys, and produced the MDN Browser Compatibility Report 2020 which listed the top five frustrations as:

  1. Having to support specific browsers (e.g., IE11).
  2. (Outdated or inaccurate documentation for frameworks and libraries.)
  3. Avoiding or removing a feature that doesn’t work across browsers.
  4. Testing across browsers.
  5. Making a design look/work the same across browsers. 

The report also noted:

We found that a lot of developers are struggling in particular with layout and styling issues: CSS Flexbox, CSS Grid and problems achieving consistent layout in recent browsers with dynamic viewport sizes and scrolling. JavaScript was often mentioned, but turned out not to be problems with the core language and instead numerous challenges with achieving browser compatibility with various Web APIs.

The response to the report was Compat 2021, a joint benchmarking initiative by Google, Mozilla, Microsoft and others which had five areas of focus:

  1. Aspect Ratio
  2. Flexbox
  3. Grid
  4. Sticky Positioning
  5. Transforms

By the end of 2021 the project was able to report scores of over 90 for the major browsers.


Building on this progress we now have Interop 2022. Apple's WebKit developers have joined the endeavour and a further 10 areas of focus have been added:

  1. Cascade Layers
  2. Color Spaces and Functions
  3. Containment
  4. Dialog Element
  5. Form Fixes
  6. Scrolling
  7. Subgrid
  8. Typography and Encodings
  9. Viewport Units
  10. Web Compat

If you visit the Interop Dashboard you can see that the progress being made across 15 key areas is currently around 73%. Firefox leads with a score of 74 while Chrome/Edge trail at 72. The score is incrementing over time as the more tests that each browser passes the higher the score.

The dashboard has feedback on the individual areas - for example for Cascade Layers you can see that Safari passes more tests with each version while Chrome/Edge went from a low score to a high one in just one version. Details of and data from the tests is also available.


In calculating the final score each of the 15 key areas is worth 6%, 30% for those from Compat 2021 and 60% for those added this year. The final 10% is for three so-called "investigation efforts" into: 

  • Editing, contenteditable and execCommand
  • Pointer and Mouse Events
  • Viewport Measurement 

These are areas that are problematic and need improvement, but where the current state of the specifications or tests aren’t yet good enough to be able to score progress using test results and the plan is that browser vendors and other stakeholders will collaborate on improving the tests and specifications for these areas, so that they could be included in future iterations of this effort.


More Information

Interop 2022 Dashboard

Interop 2022: browsers working together to improve the web for developers

Compat 2021: Eliminating five top compatibility pain points on the web

Announcing Interop 2022

Microsoft Edge and Interop 2022

Working together on Interop 2022


Related Articles

Mozilla's Browser Compatibility Project

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Last Updated ( Wednesday, 09 March 2022 )