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Text Diff Checker
Free online text diff checker. Compare two versions of any text and see exactly what changed. Line-by-line comparison with green additions and red removals.
Free
No login
100% browser-based
No data sent to servers
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What is a Text Diff Checker?
A diff shows the exact changes between two versions of text — which lines were added, removed, or modified. This is the same algorithm used by Git, GitHub pull requests, and code review tools. It's invaluable for comparing config files, spotting accidental changes in generated output, or reviewing document edits.
This tool performs a line-by-line diff in your browser using the Myers diff algorithm. Added lines are highlighted in green, removed lines in red. No text is sent to any server.
Is my text kept private when using the diff checker?
Yes — completely private. The comparison runs entirely in your browser. Neither version of your text is ever sent to any server. Safe for confidential documents, proprietary code, and contracts.
What does the diff output mean?
Lines highlighted in green (prefixed with +) were added in the modified version. Lines in red (prefixed with −) were removed from the original. Unchanged lines are shown in gray.
Can I compare code files with this tool?
Yes. The diff checker works on any plain text — code, documents, configs, JSON, markdown. Paste the content of any two text files and compare.
What algorithm does the diff checker use?
Text diff tools use the Myers diff algorithm (1986), which finds the shortest edit script (minimum insertions and deletions) to transform one text into another. It is the same algorithm used by Git, GitHub, and most version control systems. It produces a human-readable diff showing added lines in green and removed lines in red.
What is the difference between character diff and line diff?
Line diff compares entire lines and marks a line as changed if anything in it differs — good for code and structured text. Character diff (word diff) shows the exact characters or words that changed within a line — better for proofreading prose. Most tools offer both modes.
Can I use text diff to detect plagiarism?
Text diff shows differences between two specific texts, but is not designed for plagiarism detection which requires comparing against many sources. For plagiarism detection use Copyscape, Turnitin, or Google search with exact phrase quotes. Text diff is best for comparing known document versions.
How is diff used in version control (Git)?
Git runs diff between the working directory and the last commit to show what changed. git diff shows unstaged changes, git diff --staged shows staged changes. Pull request review screens (GitHub, GitLab) use diff to display changed lines side-by-side. Understanding diff output is fundamental to code review.