JSON Formatter
Format, validate and minify JSON with syntax highlighting.
Diff Checker
Paste two versions of your text and compare them line by line to see exactly what changed. Additions, deletions, and unchanged lines are color-coded so you can review differences at a glance.
How to Use This Tool
- Paste original text -- add your original or baseline text into the left panel.
- Paste modified text -- add the updated or revised version into the right panel.
- Click Compare -- hit the Compare button to generate a line-by-line diff of both inputs.
- Review the results -- green lines are additions, red lines are deletions, and grey lines are unchanged content that appears in both versions.
- Clear and start over -- click Clear to reset both panels and the diff output for a fresh comparison.
What Is a Diff Checker?
A diff checker is a tool that compares two blocks of text and highlights the differences between them. It works by running a line-by-line comparison algorithm, typically based on the Longest Common Subsequence (LCS) method, to find the minimal set of additions and deletions that transform one text into the other. This is the same fundamental approach used by version control systems like Git when showing file changes.
Diff checking is essential in many workflows. Developers use it during code review to see exactly which lines were modified in a pull request. Technical writers compare document drafts to track revisions. System administrators diff configuration files to spot unintended changes after deployments. Anyone who works with text that evolves over time benefits from being able to see precisely what changed between two versions.
This browser-based diff checker processes everything locally on your device. Your text is never uploaded to a server, making it safe to use with proprietary code, sensitive documents, or confidential configuration data. Simply paste both versions, click Compare, and the results appear instantly with clear color coding.
Frequently Asked Questions
How does the diff algorithm work?
This tool uses a longest common subsequence (LCS) algorithm to compare two texts line by line. It identifies the longest sequence of lines that appear in both versions in the same order, then marks everything else as either an addition or a deletion. The result is a minimal set of changes needed to transform the original text into the modified version.
Can I compare code with this tool?
Yes, this diff checker works with any plain text, including source code in any programming language. It compares text line by line, so it handles code just as well as prose, configuration files, CSV data, or any other text format. Paste your original code in the left panel and the updated version in the right panel to see exactly what changed.
What do the colors mean?
Green lines are additions -- text that exists only in the modified version. Red lines are deletions -- text that existed in the original but was removed. Grey or uncolored lines are unchanged and appear in both versions. This color coding makes it easy to scan through large documents and quickly locate the specific lines that were modified.
What is a diff?
A diff is the result of comparing two pieces of text to identify the differences between them. It shows which lines were added, removed, or left unchanged. Diffs are fundamental to version control systems like Git, where they are used to track changes to source code over time and to review modifications before merging them into a project.
What do additions and deletions mean in a diff?
Additions are lines that appear in the modified text but not in the original, typically shown in green. Deletions are lines that appeared in the original text but were removed in the modified version, typically shown in red. Together, additions and deletions represent the minimal set of changes needed to transform the original text into the modified version.
Can I compare files with this tool?
This tool compares text that you paste into the two input panels. To compare files, open each file in a text editor, copy the contents, and paste them into the Original and Modified panels respectively. The tool works with any plain text content including source code, configuration files, CSV data, and prose documents.
What is the unified diff format?
The unified diff format is a standardized way of displaying differences between two files. It shows changed lines with a
+ prefix for additions and a - prefix for deletions, along with context lines that appear in both versions. This format was popularized by the Unix diff utility and is the default output format used by Git when showing changes between commits or branches.