Developer
5 min read
February 10, 2026

How to Compare Two Texts and Find Differences Instantly (Free Diff Tool)

Spotting one changed word in two paragraphs by eye is nearly impossible. Here's how to find every difference in seconds, for free.

When You Need to Compare Text

  • Reviewing edits between two drafts of an article or contract
  • Comparing two versions of code or configuration files
  • Checking what changed between two exports of data
  • Verifying that a "find and replace" did exactly what you expected

    • How Our Diff Checker Works

    The Diff Checker uses a longest-common-subsequence (LCS) algorithm — the same family of algorithm behind git diff — to identify which lines are unchanged, added, or removed between two texts. Results are colour-coded:

  • Green — lines added in the new version
  • Red — lines removed from the original
  • Plain — unchanged lines

    • Step-by-Step

  • Open the Diff Checker
  • Paste your original text on the left
  • Paste the changed text on the right
  • Instantly see every line-level difference highlighted, with an added/removed count

    • Tips for Best Results

  • Diffing works at the line level — for word-level precision on a single paragraph, break it into shorter lines first
  • Use it to sanity-check automated transformations (translations, reformatting, AI rewrites) against the original
  • Combine with the Regex Tester to validate pattern-based replacements before applying them broadly

    • Frequently Asked Questions

    Does this work for code as well as plain text?

    Yes — it compares any text line-by-line, making it just as useful for code, JSON, configs, or prose.

    Is my text uploaded to a server?

    No — the comparison runs entirely in your browser using a local diff algorithm.

    What's the difference between this and git diff?

    Conceptually similar (both use LCS-based comparison), but this tool works on any two blocks of text — no repository or version control required.

    Related Tools

    After comparing, you might also like the Markdown to HTML Converter for formatting your final text, or the Regex Tester for pattern-based edits.

    Written by the GMC Tools team

    Try These Tools

    Diff Checker

    Compare two texts and instantly spot the differences

    Try free

    Regex Tester

    Test and debug regular expressions with live highlighting

    Try free

    Markdown to HTML Converter

    Convert Markdown to clean HTML with live preview

    Try free

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