Web resources for Customer Engagement

Web resources are virtual files that are stored in the Dynamics 365 Customer Engagement (on-premises) database and that you can retrieve by using a unique URL address.

Capabilities of web resources

Web resources represent files that can be used to extend the Dynamics 365 Customer Engagement (on-premises) web application such as html files, JavaScript, and CSS, and several image formats. You can use web resources in form customizations, the SiteMap, or the application ribbon because they can be referenced by using URL syntax.

The URL syntax for web resources allows for relative path references. With your development tools, you can create a group of interdependent files on a development server by using file types compatible with web resources. Then, if you use a consistent naming convention and relative path references, the website will function after you upload all the files into Dynamics 365 Customer Engagement (on-premises).

Because web resources are stored in Dynamics 365 Customer Engagement (on-premises) and are solution components, they can be easily exported and installed to on-premises deployments of Dynamics 365 Customer Engagement (on-premises) or to Dynamics 365 for Customer Engagement. Web resources are also available to users of Dynamics 365 for Microsoft Office Outlook with Offline Access when offline because they are synchronized with the user's data.

You can use the form editor to add and configure form-enabled web resources into your entity forms.

Because web resources are stored as records in the database, they can be managed programmatically by using the standard techniques to create, retrieve, and update records. Text-based web resources (JScript, CSS, XML, XSL, RESX, and HTML) can be edited and saved in the application.

Limitations of web resources

There is no type of web resource that supports the capabilities of an ASP.NET(.aspx) page to execute code on the server. Web resources are limited to static files or files that are processed in the browser. A web resource can contain code that is processed in the browser to execute web service calls to interact with Dynamics 365 Customer Engagement (on-premises) data. For more information, see Work with Customer Engagement data using web resources.

Web resources are only available by using the Dynamics 365 Customer Engagement (on-premises) web application security context. Only licensed Dynamics 365 Customer Engagement (on-premises) users who have the necessary privileges can access them.

Size limitations

The maximum size of files that can be uploaded is determined by the Organization.MaxUploadFileSize property. This property is set in the Email tab of the System Settings in the Dynamics 365 application. This setting limits the size of files that can be attached to email messages, notes, and web resources. The default setting is 5 MB.

Web resource types

You can use ten file formats to create web resources. The following table lists each file format, the allowed file extensions, and the type value that you use for each.

File File extensions Type
Webpage (HTML) .htm, .html 1
Style Sheet (CSS) .css 2
Script (JScript) .js 3
Data (XML) .xml 4
Image (PNG) .png 5
Image (JPG) .jpg 6
Image (GIF) .gif 7
Silverlight (XAP) .xap 8
StyleSheet (XSL) .xsl, .xslt 9
Image (ICO) .ico 10
Vector format (SVG) .svg 11
String (RESX) .resx 12

Reference web resources

There are several methods that you can use to reference web resources.


  • When possible, use the $webresource directive. Only references that use the $webresource directive in the site map or ribbon commands will establish dependencies. Dependencies are not created when web resources reference each other.
    • To display a Silverlight web resource outside an entity form or chart, create an HTML web resource to be the host page for the Silverlight web resource. Then use the $webresource: directive to open the HTML web resource.

$webresource directive

You should always use the $webresource directive when referencing a web resource from a ribbon control or from a SiteMap sub area. Use the $webresource directive anywhere the XML allows a URL value. The following sample shows how to use it.

$webresource:<name of Web Resource>  


When using the $webresource directive, Dynamics 365 Customer Engagement (on-premises) will create or update solution dependencies.


The Xrm.Navigation.openWebResource function will open an HTML web resource in a new window with parameters to pass the name of the web resource, any query string data to be passed in the data parameter, and information about height and width of the window.

The URL generated includes the unique GUID token so that the cached web resource will be loaded.

Relative URL

When referencing a web resource from areas that do not support using the $webresource: directive, a relative URL can be used. To enable this, we recommend that you use a consistent naming convention for the web resources that reflect a virtual file structure. The solution publisher’s customization prefix will always be included as a prefix to the name of the web resource. This can represent a virtual ”root” folder for all web resources added by that publisher. You can then use the forward slash character (/) to simulate a folder structure that will be honored by the web server.

From another web resource, you should always use relative URLs to reference each other. For example, for the web page web resource new_/content/contentpage.htm to reference the CSS web resource new_/Styles/styles.css, create the link as follows:

<link rel="stylesheet" type="text/css" href="../styles/styles.css" />  

For the web page web resource new_/content/contentpage.htm to open the webpage web resource isv_/foldername/dialogpage.htm, create the link as follows:

<a href="../../isv_/foldername/dialogpage.htm">Dialog Page</a>  


Do not use a relative URL using the WebResources folder as the root path for the URL. For example, do not use this: /WebResources/<name of web resource>. When a user belongs to more than one organization on a server, this path will always refer to the users default organization. If the user is not using their default organization and the expected web resource is not included in the user’s default organization, a “File Not Found” error occurs even though the web resource does occur in the organization the user is currently working in.

Full URL

The following sample shows the style of URL you can use to view web resources.

<Microsoft CRM URL>/WebResources/<name of web resource>  

The application will process this URL and return the file that contains the latest version of the web resource. This URL will look like this:

<Microsoft CRM URL>/%7B<version value>%7D/WebResources/<name of web resource>  

The version value is updated when you publish customizations and ensures that the browser uses the latest cached version of the web resource. Because of this, use a relative path to a web resource, the Xrm.Navigation.openWebResource function, or the $webresource Directive (when possible) because the version value will automatically be included. For large web resources there can be significant performance implications if you don’t use the cached version of the file.

The following sample shows a URL for Dynamics 365 for Customer Engagement, where MyOrganization is the name of your organization, and new_/test/test.htm is the name of the web resource:



Including the ‘/’ character and a file name extension in the name of the web resource is an optional best practice.

The following sample shows a URL for on–premises Dynamics 365 Customer Engagement (on-premises), where myServer is the server name:


When you write code to reference a web resource that will need to work for either Dynamics 365 for Customer Engagement or on–premises Dynamics 365 Customer Engagement (on-premises), you should use the getClientUrl function.

Community tools

WebResources Manager is a tool that XrmToolbox community developed for Dynamics 365 Customer Engagement (on-premises). Please see the Developer tools topic for community developed tools.


The community tools are not a product of Microsoft Dynamics and does not extend support to the community tools. If you have questions pertaining to the tool, please contact the publisher. More Information: XrmToolBox.

See also

Write Client Application Extensions for Dynamics 365 Customer Engagement
Create Accessible Web Resources
Web Page (HTML) Web Resources
Silverlight (XAP) Web Resources
Script (JScript) Web Resources
Image Web Resources
Stylesheet (XSL) Web Resources
Data (XML) Web Resources
Style Sheet (CSS) Web Resources
Web Resource Messages and Methods
Sample: Passing Multiple Values to a Web Resource Through the Data Parameter
Sample: Web Resource Utility
Sample: Importing Files as Web Resources
Use Web Service Data in Web Resources
Streamline web resource development using Fiddler AutoResponder