Diff Checker
Compare two texts side by side and see exactly what changed.
Additions, deletions, and modifications highlighted inline.
Free Online Text Diff Tool
The Toolts Diff Checker compares two blocks of text side by side and highlights the differences at both line and word level. Deleted content is shown in red on the left panel, added content in green on the right panel, and unchanged lines appear on both sides in gray. Modified lines show word-level changes highlighted inline, making it easy to spot exactly what changed.
How It Works
The tool splits both texts into individual lines and compares them using a longest common subsequence (LCS) algorithm. For lines that are similar but not identical, a secondary word-level diff highlights the specific words that changed within each line. This two-level approach — line diff plus word diff — gives you the precision to catch even small changes in large texts. It's useful for comparing code versions, checking document revisions, reviewing content edits, or verifying configuration file changes.
Features
Side-by-side comparison with synchronized line numbers. Word-level inline highlighting for modified lines. Line-numbered input editors with word-wrap support. Loading text files directly from your device. Works entirely in your browser — no data is uploaded. Fast and accurate with the LCS diff algorithm. Keyboard shortcut Ctrl+Enter to compare instantly.