I have a number of instances where SSRS reports are displayed through Page Viewer Web Parts in SharePoint. When doing so, I like to only display the report, not the header, toolbar, or parameters section. You can hide them by appending these query strings to the URL:

[shell]rv:HeaderArea=None
rv:ToolBar=None
rv:ParamMode=Hidden[/shell]

For example:

[shell]http://{SHAREPOINT_SITE}/_layouts/ReportServer/RSViewerPage.aspx
?rv:RelativeReportUrl=/Reports/report.rdl&rv:HeaderArea=None&rv:ToolBar=None
&rv:HeaderArea=None&rv:ToolBar=None&rv:ParamMode=Hidden[/shell]

That’s it.

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