Web Compatibility

A person should be able to use the Web with any devices and browsers.

Our attempt is to help both website developers and browser implementers to reach a point where users have no issues when browsing the Web because of their choices.

Our activity

The Web Compatibility activity is composed of permanent Mozilla staff and volunteer contributors. We are part of the Developer Experiences Team.

What is Web Compatibility

Web Compatibility issues are related to Web sites implementing techniques that create issues for a certain class of browsers and/or devices. A person will not be able to use a Web site according to his/her own choices.

These issues are cross-platforms, cross-products and related to the Web as a whole. There are circumstances when a company will choose to use a standardized techniques which is not available for an old browser, but that should be mitigated in making the Web site usable in any circumstances. So if a person is using the last version of Firefox or a vocal browser such as Jaws, or a proxy browser such as Opera Mini or UCWeb, the Web site should be able to work.

Mozilla has two areas for dealing with Web Compatibility issues. The goal is to make the Web usable by anyone and not only Firefox products, but we will focus the efforts on solving issues for Firefox users.

Web Compatibility issues can change over time, we keep an updated list of the most common issues.

Evolving Web Platform

Sometimes Web Compatibility issues are created by the browsers themselves when the technology evolves by either adding a new feature or deprecating a feature, if you are a browser implementer you may want to seek assistance from the Web Compatibility team to evaluate the risk of deprecating and unshipping a Web exposed feature.

Core Team

Name Matrix GitHub Role
Dennis Schubert denschub denschub Diagnosis / Site Interventions
James Graham jgraham jgraham Web Platform Test
Ksenia Berezina ksy36 ksy36 Diagnosis/ / Machine Learning
Oana Arbuzov oana softvision-oana-arbuzov Triage/Testing
Raul Bucata raulbucata softvision-raul-bucata Triage/Testing
Thomas Wisniewski twisniewski wisniewskit Diagnosis / ETP Shims


We hold Weekly meetings every Tuesday at 6am PST (if we have something to discuss).

Contact Us

Web Compatibility Taxonomy

Why sites are failing in Firefox? What can we do when this is happening?

Web Compatibility Issues

You can participate into making the Web a better place by handling these issues.

Status Bugzilla
To triage 🐝 🐝
To diagnose 🐝 🐝
Find a contact 🐝 🐝
To contact 🐝 🐝

WebCompat Tracking and Triage

Web Compatibility How-To

In case, you want to contribute time or help fix issues, you can learn how to get involved. The Web Compatibility team also participates in the Outreachy program.

Web Compatibility Summit

WebCompat Summit (2015)