Text Diff Tool
Compare two blocks of text side by side and highlight differences. Perfect for comparing code, documents, or any text content.
Text Comparison
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About Text Diff Tool
A text diff tool is a comparison utility that analyzes two blocks of text and highlights the differences between them in a clear, visual format. This tool provides side-by-side comparison with color-coded highlighting to show additions, deletions, and modifications, making it easy to identify changes in documents, code, or any text content.
Why use a Text Diff Tool?
Using a text diff tool saves time when reviewing changes, ensures accuracy in document comparisons, and prevents errors when merging content from different sources. It provides visual clarity for complex changes, helps maintain version control, and improves collaboration by making differences immediately apparent to all team members.
Who is it for?
This tool is essential for developers comparing code versions and reviewing pull requests, writers tracking document revisions, editors comparing different drafts, content managers reviewing website changes, legal professionals comparing contract versions, and anyone who needs to identify precise differences between two text documents.
How to use the tool
Paste the original text into the left input field
Paste the modified or comparison text into the right input field
Click the compare button to analyze the differences
Review the highlighted changes showing additions, deletions, and modifications
Use the visual comparison to understand exactly what has changed between versions
Frequently Asked Questions
How do I compare two pieces of text?
Paste two text versions into the left and right input areas. Click Compare and the tool shows additions (green), deletions (red), and unchanged content side-by-side with synchronized scrolling. Line-by-line and character-by-character diff modes available. Runs entirely in your browser ā your text never leaves the device. Useful for: comparing document versions, reviewing edits, finding changes between code versions, log file analysis.
What does the diff highlight?
Three categories. **Additions** (green): content present in the right side but not the left ā newly added text. **Deletions** (red): content present in the left but not the right ā removed text. **Unchanged** (default styling): content identical in both. The diff algorithm aligns the inputs to maximize matched content and highlight the actual changes. For very different inputs, the diff may show everything as deleted + everything as added (no shared structure to align).
Is my text sent to a server?
No ā diff comparison runs entirely in your browser via JavaScript. Your text never reaches a server, never gets logged. Verify in DevTools' Network tab: zero HTTP requests during comparison. Safe for comparing sensitive document versions (contracts, legal text, internal memos).
What's the difference between line and character diff?
Line diff: comparison happens line-by-line. A line is shown as 'changed' if any character within it differs ā useful when changes are paragraph-level. Character diff: comparison happens within each line, showing exact characters changed ā useful when changes are word-level edits within sentences. Most diff tools default to line diff (cleaner for code review); switch to character diff for prose editing where you want to see exactly which words changed.
Does this work for code, JSON, or natural language?
Yes ā text diff works on any text content. For code: use it to compare two versions of a function, file, or commit. For JSON: it shows added/removed keys (though [JSON Diff](/tools/json-diff/) is more structure-aware). For natural language: shows edits between draft and revised versions. For structured data where order doesn't matter (object keys), use a format-specific diff tool. For pure text where order matters (most cases), this tool works well.
How is this different from JSON Diff?
[JSON Diff](/tools/json-diff/) is JSON-aware: it understands that JSON objects are unordered ({a:1, b:2} ā” {b:2, a:1}), arrays are ordered, and structure matters. Text Diff treats everything as plain text ā '{a:1, b:2}' and '{b:2, a:1}' show as different by text diff (the byte sequences differ). For JSON comparison, use JSON Diff. For non-JSON text, code, or general comparison, use this Text Diff tool.
How large can the texts be?
Browser performance is the limit. Up to ~1 MB on each side compares in under a second. Past 5 MB, performance degrades ā the diff algorithm is O(nĀ²) in the worst case. For very large texts (log files, full codebases), use command-line tools: `diff` (Unix), `git diff`, or specialized tools like Beyond Compare or Meld. This tool fits the common case of comparing emails, documents, code snippets up to a few thousand lines.
When should I use Text Diff vs Text Diff Compare Tool?
Both tools compare text. [Text Diff](/tools/text-diff/) (this tool) is the standard side-by-side diff. [Text Diff Compare Tool](/tools/text-diff-compare-tool/) may offer additional features (statistics, similarity scoring, advanced options) depending on configuration. For most use cases, either works; pick based on the specific UI/output you prefer. For JSON-specific comparison, use [JSON Diff](/tools/json-diff/) instead ā structure-aware comparison gives better results.
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