Text Diff Checker
Compare two blocks of text side by side with color-coded additions, deletions, and inline word-level changes. Everything runs in your browser.
Paste text in both boxes to compare
Or click Sample to try it with example text.
About Text Diff Checker
Comparing two versions of text — to find what changed between drafts, what differs between configuration files, or what edits a collaborator made — is something most of us do in the dark by skimming back and forth. This text diff tool puts both versions side by side with additions, deletions, and unchanged lines visually distinguished, so you can see every change in a single pass.
Useful for reviewing edits on contracts, comparing configuration files between environments, spotting accidental changes in copy-paste workflows, and providing structured feedback on drafts. The diff happens locally, which matters when the content is confidential — legal documents, sensitive emails, internal proposals — and you cannot upload it to an online comparison tool.
How to Use
Paste the original text in the left box and the modified text in the right box.
Choose Split view (side-by-side) or Unified view (inline). Split highlights word-level changes within modified lines.
Toggle 'Hide unchanged lines' when comparing long files to focus only on what changed.
Use 'Ignore whitespace' or 'Ignore case' for more flexible comparison.
Click 'Copy Diff' or 'Download .patch' to export the result.
Frequently Asked Questions
How does the diff algorithm work?
This tool uses a Longest Common Subsequence (LCS) algorithm to align two texts at the line level. When 'Word' precision is selected, it runs a second LCS pass on adjacent modified lines to highlight only the differing words. 'Char' precision does the same at the character level.
What is the difference between Split and Unified view?
Split view shows the original text on the left and the modified text on the right in a two-column layout — best for reviewing changes line by line. Unified view shows both texts merged into a single column with additions marked '+' and deletions marked '−' — the same format git diff produces, useful for narrow screens.
What does 'word-level precision' actually do?
When a line is modified (a removed line paired with an added line), word-level precision runs a second diff pass on the two lines and highlights only the words that actually changed — instead of marking the whole line as different. This is much more useful for reviewing prose or code changes.
Can I compare large files?
Yes — the algorithm scales to files with several thousand lines in the browser. For very large files (10,000+ lines), performance may slow but still works. Everything runs client-side, so no upload size limit applies.
Is my text sent to a server?
No. The entire diff runs in your browser via JavaScript. Paste sensitive code, contracts, or documents freely — nothing is uploaded or logged.
Text Diff Checker Online: Compare Two Texts Side by Side
Spotting changes between two text versions by eye is slow and error-prone. A diff checker shows exactly what was added, removed, and unchanged in seconds.
Read the full guide