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Diff Checker FAQ — Compare Text, Code & Files Online

Q: How do I compare files in git?

Working vs staged: git diff. Staged vs commit: git diff --staged. Between commits: git diff abc123 def456. Between branches: git diff main..feature.

Q: How do I compare JSON files?

Sort keys first: diff <(jq -S . a.json) <(jq -S . b.json). Or use the Diff Checker after formatting both with the JSON Formatter.

Q: What diff algorithm does git use?

Myers' algorithm by default. Also available: patience (better for code), histogram (faster patience variant), minimal.

Q: How do I compare branches in GitHub?

URL: github.com/owner/repo/compare/base...compare. Shows all commits and file diffs. Can create a PR from this view.

Q: How do I ignore whitespace in diffs?

Git: git diff -w. GitHub PR: add ?w=1 to URL. The Diff Checker also has whitespace options.

Answers about text comparison, diff algorithms, merge conflicts, and how to compare code and documents online.

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Q1 How do I compare two texts online?

Paste original and modified text into the Diff Checker. Differences are highlighted instantly — green for additions, red for deletions. No signup required.

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Q2 What is a diff?

A diff shows differences between two texts or files — which lines were added, removed, or changed. Fundamental to version control and code review.

Q3 What is a side-by-side diff?

Side-by-side shows original and modified in two columns with aligned line numbers. Easier to read for large changes. Default in GitHub and VS Code.

Q4 What is a unified diff?

Unified diff shows changes in a single column with + for additions and - for deletions. Default git diff format. More compact than side-by-side.

Q5 How do I compare files in git?

Working vs staged: git diff. Staged vs commit: git diff --staged. Between commits: git diff abc123 def456. Between branches: git diff main..feature.

Q6 How do I resolve a merge conflict?

Find conflict markers, choose the correct version (or combine both), remove markers, git add, git commit. VS Code has a visual merge editor.

Q7 How do I compare JSON files?

Sort keys first: diff <(jq -S . a.json) <(jq -S . b.json). Or use the Diff Checker after formatting both with the JSON Formatter.

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Q8 What diff algorithm does git use?

Myers' algorithm by default. Also available: patience (better for code), histogram (faster patience variant), minimal.

Q9 How do I compare branches in GitHub?

URL: github.com/owner/repo/compare/base...compare. Shows all commits and file diffs. Can create a PR from this view.

Q10 How do I ignore whitespace in diffs?

Git: git diff -w. GitHub PR: add ?w=1 to URL. The Diff Checker also has whitespace options.

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Q11 How do I compare files in VS Code?

Right-click first file: Select for Compare. Right-click second: Compare with Selected. Or use Source Control panel for git changes.

Q12 What is a three-way merge?

Compares two modified versions against their common ancestor. If only one side changed a line, that change is accepted automatically.

Q13 How do I compare Word documents?

In Word: Review then Compare. For plain text: copy content into the Diff Checker.

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Q14 What is a semantic diff?

A semantic diff understands code structure (AST-based) rather than comparing raw text. Can detect moved functions or renamed variables. Tools: difftastic, GumTree.