How MDN and Web Platform Docs Align

We have been asked a number of questions since the launch of Web Platforms Docs (WPD) about how it aligns with the Mozilla Developer Network (MDN). Questions such as how content will be shared between the two, how changes will be tracked, who will do the work to port content, and which site people should contribute to. To try and help answer some of these questions, we’ve put together this short FAQ.

Before we dive into these, it’s worth underscoring that Mozilla sees MDN and WPD complementing each other. While WPD is just starting out on its journey to become an invaluable resource for developers, MDN is fully mature and will continue to serve needs that WPD doesn’t. We also want to take this opportunity to remind people that Mozilla is community driven, so any decisions to change what we’re doing will be based on community feedback.

Here are the top questions we’re getting on the introduction of WPD. If you have additional questions, post a comment or email jswisher (at) mozilla (dot) com.

MDN and WPD seem to have similar goals. How are they different?

Mozilla supports WPD because it fits with Mozilla’s mission to promote openness and innovation on the Web. WPD has the benefit of financial support, content contributions, and perspectives from multiple browser vendors and Web-oriented companies. MDN has a long history of supporting developers of many stripes: Web developers, developers who use Mozilla code, and developers who work on Mozilla code. MDN promotes Mozilla’s mission by serving all these audiences.

One difference is in the default licenses for reuse of the content from the two sites, although they are both Creative Commons licenses. MDN uses a CC-BY-SA license, which ensures that reused content will always be published in the context of an openly licensed work. WPD uses a CC-BY license, which enables the content to be reused as widely as possible, including potentially in the context of otherwise proprietary works.

Why support two similar sites? Isn’t there a lot of topical overlap?

WPD is in its infancy, and will take time to gather momentum, soothe teething problems, and foster a community, which Mozilla and other WPD stewards will help to do. Meanwhile MDN needs to support the hundreds of thousands of developers who visit it every week.

As WPD matures, the MDN community will evaluate if and when it makes sense to defer to it on particular topics. In an ideal future, WPD would become the authoritative resource on Web standards, with a large volunteer community and community-based governance, while MDN could focus on Mozilla’s vision and its open source products that implement those standards. But it will take some time to get there.

WPD launched its site as a “minimum viable product”, providing just enough features to get started. This is a prudent and reasonable strategy, so that feedback can help determine how the site is developed. However, it means that WPD is currently lacking desirable features that will be added later. Key among these missing features is support for translating articles into other languages, to help Web developers whose native language is not English.

Meanwhile, due to its long head start as a Web resource, MDN offers translations in multiple languages, which are created by global communities of volunteer localizers, who prioritize translation of topics based on local needs and interests. As with English content, the localization communities will evaluate whether and when it makes sense to defer to content on WPD.

Can MDN content be copied to WPD? Who is going to do the work of porting MDN content to WPD?

Anyone working on articles on a given topic on WPD is more than welcome to incorporate content from MDN, as it makes sense to do so. Rather than exporting MDN content into WPD, wholesale, we hope that it will be curated by WPD authors into the appropriate context on the new site.

Please be sure to following the licensing and attributing guidelines for MDN content on This is needed because of the different licenses for the sites’ content; MDN content on WPD must be delineated and attributed, to ensure proper credit to MDN authors, and to convey the share-alike license requirement.

Will duplicated content in both sites be automatically kept in sync?

There’s no technical solution to do this at this time. We expect that each site’s content will evolve independently.

Doesn’t that mean that there will be redundant work to keep both of them updated, especially as browsers and standards progress?

Yes, unfortunately. There may eventually be areas where the sites can share information, such as browser compatibility data.[1] That has yet to be worked out.

Are the stewards just turning WPD over to “the community” or are they devoting staff to it?

Mozilla has paid staff participating in the WPD community in addition to working on MDN. Chris Mills of Opera is spending half of his time as a W3C Fellow, with a focus on WPD. Other stewards, as well as W3C, also have staff working on WPD; you’d have to ask them about their time allocation. However, contributions from Web developers, writers, educators, and others who are not paid staff of stewards are essential to the long-term success of WPD (as well as that of MDN). If only steward-paid staff contribute, it will not achieve its vision to be a truly open community resource.

I want to contribute to Web standards documentation. Should I contribute to MDN or to WPD?

Both sites could use your help, and Mozilla is contributing to both sites. MDN has an established community and lots of open documentation for the Web, which always needs improving, expanding, and translating. We will continue to build that community and give them a place to learn and share knowledge about the Web. WPD’s community is still forming, and could use your input into basic issues like information architecture and the translation scheme. WPD aims to bring together tutorials and materials from many different organizations, as well as contributions from Web developers, and we believe that will also support the open Web. Check them both out. Meet the communities. Join in where you feel comfortable.

Here are some channels for getting involved:

  Mozilla Developer Network Web Platform Docs
Introduction to contributing Getting started Getting Started Guide
Mailing list
IRC channel

#devmo on #webplatform on

[1] Specifically, MDN has lots of manually collected cross-browser compatibility data, which WPD can use now; WPD is looking at ways to automate collecting such data, which MDN could then also use.


  1. Bob Pelerson

    “MDN uses a CC-BY-SA license, which ensures that reused content will always be available under an open license. WPD uses a CC-BY license, which enables the content to be reused as widely as possible, including potentially in otherwise proprietary works.”

    This is a bogus myth and should not be perpetuated. Content under a CC-BY license will always be available under an open license, no matter who uses it for what purpose. This is the point of the license. Content under the CC-BY-SA is will be available, but restricted in some uses. In particular it makes it disincentives adding additional content.

    It is important to never claim or pretend that CC-BY can ever become non-open-source or non-free. This is just not true.

    December 18th, 2012 at 09:59

    1. Janet Swisher

      Thanks for your feedback, Bob. Would you agree with the statement that “CC-BY-SA ensures that the reused content will always be published in the context of an open-licensed work”? I can update the post.

      December 18th, 2012 at 10:08

      1. Bob Pelerson

        Yes, this is an accurate statement.

        December 18th, 2012 at 10:17

        1. Janet Swisher

          I’ve updated that section of the post.

          December 18th, 2012 at 10:26

  2. Anders

    The stated goals of MDN and WPD do indeed seem to be similar. If Mozilla truly backs WPD, the content for the topics that are shared (that is the web standards and not the Mozilla technologies) will be moved from MDN. Having duplicate or shared content makes no sense and is hurting the web (or at least the WPD effort).

    > Key among these missing features is support for translating articles into other languages, to help Web developers whose native language is not English.

    Translating developer documentation is probably a good way of rallying the translators and creating a community around them. But for better or worse English is the lingua franca of web and in particular developers, so it is at best of no benefit to developers and probably a disadvantage since the translated sections may not be compete or up to date, yielding incomplete and stale information, and the translated pages may show up as noise in the search results. So translation features should not keep the moving of content back.

    December 18th, 2012 at 13:34

    1. Janet Swisher

      Hi Anders, thanks for your comment.

      English may be the lingua franca of the Web, but that doesn’t mean that everybody reads it equally fluently. Some Web developers are self-taught, don’t have a university education, or have one where English wasn’t emphasized. For example, I have heard from some Mozilla community members who are not native English speakers that they can get by with reference docs in English, but that for conceptual docs or tutorials, their native language is more comfortable. Of course, with volunteer translators, there is a risk that the translations may fall out of date, especially if a few key people drop out. Our enhancement backlog for MDN includes tools to help translators track what needs updating, which we hope to implement in 2013.

      As you say, translation is orthogonal to what happens to content in English. Part of the purpose of this post is to get a sense of sentiment from our Web developer audience.

      December 18th, 2012 at 19:08

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