I tested three plugins. All of them have above 4 star rating, but after using them, one of them (Search Regex) clearly stands out compare to the other two. Reasons are listed below.

Search Regex : simple interface, easy to use. It supports powerful regular expressions, and allows you to test the query. The execution speed is very fast. Highly recommended. image
Search & Replace: the interface is more complicated. Allow testing, but speed is slow in returning the results. I made several mistakes using this plugin. image
Find and replace: simple interface, but not sure if it supports search without replacement. The help document does not clearly state that. I didn’t try to use it. image

Recommendation: use Search Regex for search and replace strings in your wordpress blog.

Written by Shengdong Zhao

Shen is an Associate Professor in the Computer Science Department, National University of Singapore (NUS). He is the founding director of the NUS-HCI Lab, specializing in research and innovation in the area of human computer interaction.