Text Diff & Comparison Checker
Visual word-by-word and line-by-line text difference checker. Compare contracts, code, and copy with green and red change highlighting.
About this tool
How to use it
- Paste your original baseline text into the left pane and the modified version into the right pane.
- Select your comparison granularity: Word-by-Word for documents and legal contracts, Line-by-Line for code, or Character-by-Character for subtle typos.
- Toggle case sensitivity or whitespace normalization as needed.
- Review visual diff highlights (soft green for additions, red strikethrough for deletions) and copy the structured diff report.
Why it matters
Manual side-by-side text proofreading is slow and notorious for overlooking subtle alterations in multi-page documents. Visual diffing pinpoints exact insertions, deleted phrases, and modified terms instantly, protecting parties from unannounced contract redlines and catching accidental copy regressions.
When to use it
Use this tool before signing revised legal agreements, verifying SEO meta tag revisions, auditing code configuration diffs, checking student essay revisions, or comparing software release notes.
Good to know
The diff engine uses the Longest Common Subsequence (LCS) algorithm running 100% client-side in your browser. Confidential contract terms, private passwords, and sensitive proprietary code are never transmitted over the network.
Common questions
What algorithm powers this text difference checker?
It utilizes the Longest Common Subsequence (LCS) dynamic programming algorithm, computing the shortest sequence of edit operations (insertions and deletions) required to transform the original text into the revised text.
Can I compare code and JSON configs line by line?
Yes. Switch the Granularity dropdown to 'Line by Line'. The diff engine will treat entire code lines as atomic tokens, highlighting added and removed lines without splitting individual code tokens.
Is my text private and secure?
Yes. The entire diff calculation executes locally in your browser's JavaScript sandbox. No input data, drafts, or output reports are ever sent to an external server or saved in a database.
What does the similarity percentage mean?
The similarity percentage reflects the proportion of identical tokens shared between both texts. A 90% score indicates that 90% of the content remains unchanged between the two versions.