Question 1

What is a diff checker used for?

Accepted Answer

A diff checker compares two pieces of text or code and highlights the differences between them. It is commonly used for code reviews, comparing document versions, tracking changes, merging files, debugging configuration files, and quality assurance testing. Learn more in our guide on [what is a diff tool and when should I use it](/blog/what-is-a-diff-tool-and-when-should-i-use-it).

Question 2

How do I compare two text files online?

Accepted Answer

To compare two text files online: 1) Paste or upload your first file into the left panel, 2) Paste or upload your second file into the right panel, 3) Click Compare to see differences highlighted. Added lines appear in green, removed lines in red, and modified lines in yellow. The side-by-side view makes it easy to spot every change. Also useful for comparing [JSON](/tools/json-formatter) or [YAML](/tools/yaml-json-converter) configurations.

Question 3

How does the diff algorithm work?

Accepted Answer

Our diff checker uses a line-by-line comparison algorithm that identifies added, removed, and modified lines. It highlights changes in different colors: green for additions, red for deletions, and yellow for modifications. The tool preserves formatting and indentation to show exact differences. Learn about different algorithms.

Question 4

Can I compare code files with syntax highlighting?

Accepted Answer

Yes! The diff checker supports syntax highlighting for many programming languages including JavaScript, Python, Java, C++, PHP, Ruby, and more. This makes it easier to spot code changes while maintaining readability.

Question 5

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

Accepted Answer

Side-by-side diff shows both versions in parallel columns, making it easy to visually compare line by line. Unified diff (patch format) shows changes in a single column with + and - prefixes, commonly used in Git and version control. Our tool provides side-by-side visualization for easier reading. Learn more in our [diff tool guide](/blog/what-is-a-diff-tool-and-when-should-i-use-it).

Question 6

Is my code safe when using this tool?

Accepted Answer

Absolutely. All comparisons happen entirely in your browser using JavaScript. Your code and text never leave your device - nothing is uploaded to our servers. The tool runs completely client-side for maximum privacy and security.

Question 7

Can I ignore whitespace when comparing files?

Accepted Answer

Yes, the diff checker has an option to ignore whitespace differences. This is useful when comparing files that may have different indentation styles or trailing spaces but are otherwise identical. Enable "Ignore Whitespace" to focus on meaningful content changes.

Question 8

Can I export or share the diff results?

Accepted Answer

You can copy the comparison results to your clipboard or export as a .diff file. The tool shows a visual side-by-side comparison that you can share with team members for code reviews or documentation purposes.

Question 9

How do I compare JSON files for differences?

Accepted Answer

Paste your JSON content into both panels and click Compare. The tool highlights structural differences including added/removed keys, changed values, and modified arrays. For better readability, first format your JSON using our [JSON Formatter](/tools/json-formatter) to ensure consistent indentation before comparing.

Question 10

What is the best way to compare configuration files?

Accepted Answer

For configuration files (YAML, JSON, .env, nginx.conf), enable "Ignore Whitespace" to focus on meaningful changes. Use line-by-line diff mode to see exactly which settings changed. The side-by-side view makes it easy to spot misconfigurations before deploying to production.

Question 11

Can I compare Git commits or branches?

Accepted Answer

While this tool compares text directly, you can copy content from different Git commits or branches to compare them. For Git-specific diffing, use git diff in your terminal or your IDE's built-in Git tools. This online diff checker is useful when you need to quickly compare snippets without accessing Git.

Diff Checker

Diff Checker - Free Online Text & Code Comparison Tool

Example: Code Comparison

What You Can Do:

Supported Languages:

Need Help with Code Reviews or Version Control?

Understanding Diff Tools

Common Use Cases

Reading Diff Output

Frequently Asked Questions

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