Guidelines for add-on developers

September 9th, 2009

It’s well understood that the typical computer users today spend much of their time in their web browser, making it the most important software on their computer. Users expect their browsers to be easy to use, fast, stable and secure.

Over the past few months, users have downloaded thousands of great browser add-ons from and other web sites. Users want to use browser add-ons to enhance their browsing experience, not hinder it or make it more confusing.

We have published a full list of guidelines to help add-on developers create quality add-ons. We created these guidelines to respond to demand from the developer community and to help share the thinking of the IE team, gathered from years of providing support to users and developers. We strongly recommend that developers follow these guidelines when developing add-ons for IE users. We occasionally come across add-ons that violate these guidelines so egregiously that we treat them as malware; on the other hand, we frequently see really helpful and creative add-ons that put the “user in control” and enhance the browsing experience. Here are the core aspects of our guidelines:

Do not limit the user’s ability to access Internet Explorer features

Users require access to the entire set of Internet Explorer features, including but not limited to: the address bar, search box and new tab page to navigate and search the Internet easily and safely. Users expect these features to be available to them at all times and our support data shows that users are confused and unhappy when these features are obscured or changed. Please don’t write add-ons that hide, obscure or limit access to Internet Explorer features.

Do not limit the user’s ability to control Internet Explorer settings

It’s important that users be able to control their browsing experience. We’ve provided many configuration options for IE users to help them set up their browser exactly how they want it and protect themselves from potentially harmful malware. (See previous my previous post on toolbars and search defaults)

To support this guideline, add-on software should not remove or limit the user’s ability to view and modify IE settings.

Only use supported APIs

Add-ons should only use supported Internet Explorer and Windows application programming interfaces (APIs), detailed on MSDN. Using an unsupported method of extending Internet Explorer or relying on implementation details in a specific version of IE may cause browser stability problems when Internet Explorer is updated. Also, when two add-ons try to use the same unsupported method of extending Internet Explorer they might crash the browser – our APIs are specifically designed to prevent this kind of problem.

Microsoft is committed to working with all add-on software developers to ensure that our mutual customers – you, the user – have a great experience when using Internet Explorer with add-ons. If you are developing or maintaining an Internet Explorer add-on, please review our guidelines and ensure that your add-ons deliver a good long-term experience for users.

Thank you,
Frank Olivier and Herman Ng
Internet Explorer Program Management