Comparator (Plain Text) is a free, web-based tool designed to run in a browser window. It is easy to use, designed to compare the text of two documents, either hosted at a web address or uploaded from the user's files.

Users may set the comparison criteria. Options include all words, words matching a pattern, words in or excluded from a user-specified list, or excluded from the Glasgow stop word list. The second text can be plain text, HTML or XML; the tool will treat HTML and XML documents as plain text. Searching a pattern rather than a word requires skill with regular expressions and is thus not accessible to all users.

Other features include options to sort by the first text’s word count or ratio of relative word count, and to display as HTML or a tab delimited text. The HTML output gives several tables of information about the texts, including basic information about the texts, a word comparison, words in the first text, and words in the second. Any of the words in the word comparison table may be clicked to produce a concordance for that word.

This tool has a few problems. When the tab delimited output is selected, the tool may not process some characters correctly; please see List Words (Plain Text) for examples. In addition, punctuation like open quotes and long dashes are often appended to the adjacent word, skewing the counts and comparison.

Despite these issues, Comparator (Plain Text) is an effective way to make a comparative analysis of two texts. Versions are also available for HTML and XML documents.