Add-Meta-Tags, since January 2006, has been designed to be compatible with any other WordPress plugin, free or commercial, by strictly following the plugin development guidelines, which are suggested by the WordPress Project, in order to avoid conflicts with other plugins the users might have activated in their WordPress platforms.
Add-Meta-Tags respects the users' freedom to choose the plugins that help them better meet the needs of their web sites. It never issues any warning messages about 3rd party plugins. It never affects/hijacks/overwrites/replaces the functionality of other plugins in any way possible. Its source code is publicly available in its entirety for anyone to review.
From a technical point of view, Add-Meta-Tags is 100% safe to use in any WordPress based environment with any number or type of other plugins activated, regardless of their functionality and feature sets.
However, there are many plugins out there, the feature sets of which may contain features similar to some of the features of Add-Meta-Tags. Therefore, it is possible, if the user enables similar features in multiple plugins, duplicate meta tags to appear in the HTML head area or the HTML body area of the web page. This could confuse search engines and lead to unexpected results SEO wise.
In order to help users avoid the possibility of having duplicate meta tags in their web pages and, at the same time, respect the users' freedom to mix features of multiple plugins in any way they see fit, Add-Meta-Tags allows the user to deactivate any of the supported metadata generators and also any of the Metadata box features in the post editing screen. This provides users with all the flexibility they might require in order to use the features they want.
Furthermore, Add-Meta-Tags offers the opportunity to customize its functionality to a great extent via filtering functions that can be attached to the various filter hooks that are spread throughout the code.
Add-Meta-Tags can be adapted to co-operate flawlessly with any other web site optimization plugin.
Being compatible with other WordPress plugins is a matter of principal for the Add-Meta-Tags development and, also, a high priority goal that must be met in every release.