Online Text Diff & Comparison Tool
Find differences between two blocks of text or code instantly. Clean side-by-side and unified views with intra-line word highlighting and 100% client-side privacy.
At a glance
Text Diff & Comparison Tool is a free online tool that compares two text snippets or code files side-by-side with word-level difference highlighting. It switches between split parallel columns and linear unified diffs with line numbers. Highlights exact words and tokens altered within modified lines for granular clarity. All processing is local: nothing is uploaded, and no account is required.
100% Client-Side Text Diff & Comparison
All diff computations run locally in your browser memory. Your confidential code, legal contracts, and text files never touch external servers.
How Does Text Diffing Work?
Text comparison relies on finding the Longest Common Subsequence (LCS) between two sequences of lines. By identifying segments that remained unaltered, the engine computes the minimal sequence of additions and deletions needed to transform Text A into Text B.
Common Use Cases
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Code Reviews & Merge Conflicts: Inspect JavaScript, Python, HTML, CSS, or SQL query differences before committing code.
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Legal Agreement & Contract Auditing: Catch subtle clause modifications, altered liability amounts, and modified terms across contract revisions.
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Content Proofreading: Pinpoint edits made during collaborative writing, essay revisions, or blog drafts.
Frequently Asked Questions
Is my sensitive code or confidential text uploaded to any server?
No. All text parsing, line tokenization, and LCS difference calculations are performed 100% locally in your browser memory. No data is ever transmitted over the network.
What is the difference between Side-by-Side and Unified views?
Side-by-Side (Split) presents Original and Modified texts in two parallel columns, making visual comparisons easy. Unified view shows all changes linearly in a single column with classic standard Git diff (+/-) markers.
Can I compare files of different programming languages or file formats?
Yes. The engine treats all inputs as plain text lines, making it universal for JavaScript, Python, JSON, Markdown, YAML, SQL, CSS, or prose.
What does "Ignore Whitespace" do?
It collapses consecutive spaces and strips leading/trailing space when matching lines, allowing you to ignore cosmetic indentation changes and focus purely on substantive code modifications.
Why Use This Text Diff & Comparison Tool?
How to Use Text Diff & Comparison Tool
Enter or Upload Texts
Paste or upload your original document on the left and the modified version on the right.
Select Diff View Mode
Choose between Side-by-Side parallel view or Unified inline view, and configure whitespace options.
Review Differences
Inspect additions highlighted in green, deletions in red, and copy or export the unified diff.
Worked example: Fox Sentence Word-Level Comparison
The engine runs an LCS dynamic-programming matrix over lines then tokenizes changed lines into words for intra-line highlighting, rendered as side-by-side or unified HTML.
Original: The quick brown fox Modified: The quick red fox jumps
2 changed tokens highlighted: brown to red; stats: 1 equal line, 1 modified line, word-level marks
Technical Specifications & Engine Details
| Specification | Details |
|---|---|
| Supported Formats | TEXT → TEXT |
| Execution Mode | 100% Client-Side In-Browser (client) |
| Browser Requirements | Requires modern web browser with ECMAScript 6+ and standard DOM Web APIs. |
| Performance Constraints | Client browser memory limit (typically 1–2 GB RAM); processing speed depends on local device CPU. |
100% Client-Side Privacy Guarantee
All text comparisons and line diff calculations are performed entirely in your browser memory. Zero content is transmitted to external servers.
Frequently Asked Questions
Is my code or confidential text uploaded to any server?
Which file formats can I compare?
How does the intra-line word diff work?
Can I ignore indentation or whitespace changes?
Methodology
This tool runs entirely in your browser. The example above shows a representative input and the result it produces.
Last updated .