With this custom activity for more complex string activities. This plugin comes with the following features.

• Append Prefix If Missing
• Append Suffix If Missing
• Capitalize
• Count Occurrences
• Does Not End With
• Does Not Start With
• Get Default If Empty
• Get Empty String If Null
• Is Email Address
• Query String To Dictionary
• Remove Prefix
• Remove Suffix
• Reverse

I've built the custom activity based on the https://github.com/timothymugayi/StringExtensions library