Question 1

What is a diff checker?

Accepted Answer

A diff checker compares two text files or strings and shows the differences between them — which lines were added, removed, or unchanged. It is widely used by developers to review code changes, compare configuration files, and track document revisions.

Question 2

What algorithm does this diff checker use?

Accepted Answer

This tool uses the Longest Common Subsequence (LCS) algorithm, the same underlying approach used by Git's diff. It finds the optimal set of changes — the minimum number of lines that need to be added or removed to transform text A into text B.

Question 3

How do I read the diff output?

Accepted Answer

Lines marked with + (green) exist only in the changed version (B). Lines marked with − (red) exist only in the original version (A). Lines with no marker are unchanged and appear in both.

Question 4

Is my text kept private?

Accepted Answer

Yes. All comparison happens in your browser — no text is sent to any server. Your data never leaves your device.

Diff Checker

Diff Checker