Diff

Text Diff Checker

LOCAL · Browser-Only

Compare two texts and see the differences highlighted

Original Text

0 lines · 0 chars

Modified Text

0 lines · 0 chars

Ignore whitespaceIgnore caseIgnore line endings

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What is Text Diff Checker?

Free online text diff checker to compare two blocks of text side by side and instantly see what changed between them.

Added lines are highlighted in green, removed lines in red, and unchanged lines are shown normally with line numbers on both sides. Switch between unified and side-by-side views, and turn on word-by-word highlighting to pinpoint the exact characters that changed within a line. Toggle ignore-whitespace and ignore-case to skip cosmetic differences, and enable syntax highlighting for JavaScript, TypeScript, Python, JSON, XML, YAML, SQL, and more. Perfect for comparing two text files, code revisions, JSON and XML configs, document drafts, contract versions, or resolving merge conflicts. Compare two versions of code, find differences between two text files, or diff two lists line by line. When you are done you can copy the result, download it as a standard .patch file, or copy it as a Markdown diff block ready to paste into a GitHub issue or pull request. The diff algorithm runs entirely in your browser - your text is never sent to any server. No signup required.

How to Use Text Diff Checker

1Paste your original text into the left textarea labeled 'Original Text'
2Paste the modified text into the right textarea labeled 'Modified Text'
3Click 'Compare' to generate the diff output
4Review the highlighted results: red for removed lines, green for added lines, and plain for unchanged lines

Frequently Asked Questions

What is a diff checker?

A diff checker compares two pieces of text and highlights the differences between them. Lines that were removed from the original are shown in red, lines that were added in the modified version are shown in green, and unchanged lines are displayed normally. This is the same concept used in version control systems like Git.

How does the diff algorithm work?

This tool uses a Longest Common Subsequence (LCS) based algorithm to find the optimal set of changes between the two texts. It compares the texts line by line and identifies which lines were added, removed, or kept unchanged, producing a minimal and accurate diff output.

Can I compare code with this tool?

Yes. The diff checker works with any plain text including source code, configuration files, JSON, XML, CSV, and more. It preserves whitespace and indentation so you can see exactly what changed in your code, with optional syntax highlighting for over a dozen languages.

How do I compare two JSON or XML files?

Paste the first file into the Original panel and the second into the Modified panel, then click Compare. The tool diffs them line by line and can syntax-highlight JSON, XML, YAML, and other formats. For structural JSON differences, format both files first so key ordering and indentation match.

What is the difference between unified and side-by-side view?

Unified view stacks all lines in a single column with + and - markers, the same layout Git uses in the terminal. Side-by-side view places the original on the left and the modified version on the right so you can scan changes column by column. Both views support word-level highlighting that pinpoints the exact characters that changed within a line.

Can I ignore whitespace or case when comparing?

Yes. Toggle 'Ignore whitespace' to skip differences in spacing and indentation, and 'Ignore case' to treat uppercase and lowercase as identical. This is useful when reformatting code or comparing text that was reindented but not functionally changed.

Can I export the diff or share it?

Yes. You can copy the diff output, download it as a standard .patch file for use with git apply, or copy it as a Markdown code block ready to paste into a GitHub issue, pull request comment, or Stack Overflow answer where it renders with red/green highlighting.

Is my text data safe?

Absolutely. All comparison processing happens locally in your browser using JavaScript. Your text is never transmitted to any server, making this tool safe for comparing sensitive or proprietary content.

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Keep reading: Bash/Shell Cheat Sheet and working without uploading reference. Doing this in code instead? See the JSON and data endpoints.

What is Text Diff Checker?

Free online text diff checker to compare two blocks of text side by side and instantly see what changed between them.