Diffing
Compare 2 text files
Compare two text files or strings side-by-side with line numbers and highlighting.
Paste or upload two files to see highlighted changes.
About Text Diff Viewer
Use this online Text Diff Viewer to compare files and identify every text difference instantly. Whether you are debugging code, checking versions, or merging content, our tool highlights exactly what has changed between your two inputs. It identifies added, removed, and modified lines with clear, distinct colors for easy analysis.
Save valuable time during code reviews and document revisions by spotting discrepancies immediately. Instead of manually scanning for errors, you can rely on this automated file diff tool to catch even the smallest whitespace changes or typos. It is an essential utility for developers, writers, and data analysts who need to highlight changes accurately.
Simply paste your original text into the 'Left' panel and the modified text into the 'Right' panel. Alternatively, upload two files from your computer. The comparison will run automatically in your browser. Use the summary view to jump between differences or toggle "Word Wrap" to view long lines comfortably.
Under the Hood
This tool uses the Myers Diff Algorithm (via the `diff` library) to compute the shortest edit script (SES) between two sequences. It operates in O(ND) time, offering a balanced approach for standard text files. The results are transformed into a unified view where chunks are tokenized and highlighted. Large files are processed in chunks to prevent blocking the main thread, though very large datasets (>5MB) may still impact UI responsiveness depending on browser allocations.