Text Diff Checker
Compare two pieces of text line by line and see what was added and removed, with options to ignore whitespace and case.
Free · No sign-up · Your inputs stay in your browser
Input
Compare two texts line by line
Output
+2 -1
Runs in this browser. Nothing you paste is sent to a server.
About this tool
Method, assumptions, practical next steps, and limits.
Comparing configuration
Most diffs a developer runs outside Git are of configuration: a production .env against staging, two nginx.conf files, the output of the same command on two servers. Sort both sides first (the line tool does it) when order does not matter, and ignore whitespace when one side was reindented.
The algorithm
A longest common subsequence diff is the textbook method. Git defaults to the Myers algorithm, which finds a shortest edit script and usually gives the same result; on code with many repeated lines such as braces, git diff --histogram often reads better. For files, git diff --no-index a.txt b.txt works outside a repository.