Suggestion for a rack feature (could be paid):

Search and replace for web content. (regexp compatible]

Description: Replaces every occurence of "Naughtyword" with "Nau***word" on every response from any webpage from site1.com and site2.com
[Example rule 1]
Search for: [Naughtyword]
Replace with: [Nau***word]
Apply to: [site1.com,site2.com]
Direction: [dropdown:[incoming]]

Description: Replace every occurence in POST data, of "cc=(any combination of numbers and spaces and dashes, anywhere from 16 to 19 chars long)", with "cc=0000000000000000", on any request.
[Example rule 2]
Search for: [cc=[0-9 -]{16,19}]
Replace with: [cc=0000000000000000]
Apply to:[*]
Direction: [dropdown:[outgoing]]

Description: Makes passwords visible (not hidden by stars) on any login form served by site_where_users_are_struggling_to_enter_password.com
[Example rule 3]
Search for: [<input([^>]+)type=(['"]?)password(['"]?)([^>]*)]
Replace with: [<input$1type=$2text$3$4>]
Apply to: [site_where_users_are_struggling_to_enter_password.com]
Direction: [dropdown:[incoming]]