There is a built-in Code Syntax Highlighter in the Umbraco 8 RichText Editor, it just needs to be activated (see Umbraco documentation)
Add SyntaxHighlighter to your Blog Posts in Umbraco 7 with this RichText Editor plugin.
Based on Alex Gorbatchev's work, this plugin enables you to paste your code into the TinyMCE based Rich Text Editor while setting common options along the way.
Although this package automatically installs SyntaxHighlighter into your /scripts folder, you will still need to include the SyntaxHighlighter scripts and configure it in your Views.
More information on the SyntaxHighlighter is available here:
Code pasted in is wrapped in <pre> tags with the appropriate brush and options required by SyntaxHighlighter.
To complete installation you will need to do two things:
These steps are detailed on the product page at http://digitalsmith.com.au/code/syntax-highlighter-for-umbraco-7.