toololis
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Text Diff Checker

Compare two texts and highlight the differences

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Free text diff checker — compare two texts line by line
 
 Toololis Text Diff Checker compares two texts and highlights what changed. Supports three granularities: line-by-line (for code and structured content), word-by-word (for prose edits), and character-by-character (for detecting subtle whitespace changes). Powered by the Myers diff algorithm — the same one Git uses.

 
Three diff modes
 
     
  • Line diff — Compares full lines. Ideal for code, logs, config files.
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  • Word diff — Compares individual words. Best for proofreading, copy edits.
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  • Char diff — Compares every character. Finds typos, whitespace, invisible changes.
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How to use this tool
  1. 1
    Paste both texts
    Drop your original text into the left box and the modified version into the right box.
  2. 2
    Pick granularity
    Line-by-line (default) compares whole lines. Word-by-word highlights smaller changes inside each line. Character-level shows every single change — best for short strings.
  3. 3
    Read the diff
    Red highlights = removed. Green highlights = added. Click Swap to flip left and right, or Clear to start over.
 
Color coding
 
     
  • Green — Additions in the modified version (not in original)
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  • Red — Deletions from the original (not in modified)
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  • Default color — Unchanged text present in both versions
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When to use a text diff
 
     
  • Code reviews — Quickly spot changes in a pull request
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  • Contract review — Compare legal document revisions
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  • Content edits — See what an editor changed in your draft
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  • Config auditing — Diff before and after a config change
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  • Translation QA — Compare corrected translation vs. machine output
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Frequently Asked Questions
How does the diff algorithm work?
We use the Myers diff algorithm (the same one used by Git) via the open-source diff JavaScript library. It finds the shortest edit sequence between two texts — the minimum number of insertions and deletions to transform one into the other.
Can I compare code with this?
Yes — it handles any plain text, including code. For syntax-aware diffing (that understands language structure), use IDE tools or git diff. This tool treats text as text, which is fine for most review and proofreading.
What's the difference between line-mode and word-mode?
Line-mode compares whole lines — best for code, logs, or any line-structured content. Word-mode compares individual words — useful for prose edits where one line has many small changes. Character-mode shows every single character change — ideal for detecting subtle whitespace or typo changes.
Does this handle large files?
Practical limit is about 1 MB per side on desktop (hundreds of thousands of lines). Beyond that, the diff becomes slow. For massive files, use command-line diff or Git.
Is whitespace included in the comparison?
Yes, exact character-for-character. Trailing spaces, tabs vs spaces, and trailing newlines all count as differences. This is accurate but can create "noise" when the real changes are more semantic.
Is my text private?
Completely. The diff runs in your browser. Nothing is uploaded or logged. Safe for comparing private contracts, code diffs, or confidential documents.
 
 
  
 

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 100% Privacy. This tool runs entirely in your browser. Your data is never uploaded to any server.