Text Diff Checker
About this tool
A text diff tool compares two pieces of text line by line and highlights additions, deletions, and unchanged content. It reproduces the same view you get from git diff or a code review tool, but works on arbitrary text — useful when the content is not in version control yet, or when you need to compare two configuration snippets, two API responses, or two translations.
How to use
- Paste the original text into the left input.
- Paste the new or modified text into the right input.
- Click Compare to render the unified diff below.
- Read green lines as additions and red lines as deletions; identical lines are dimmed.
- Use the result to spot regressions, validate translations, or document a change.
Common use cases
- Comparing the response of an API before and after a backend deployment.
- Reviewing two versions of a contract or copy block side by side.
- Checking what changed in a YAML / JSON configuration file.
- Verifying that a refactored function produces identical log output.
- Spotting subtle differences between two SQL query plans.
- Catching whitespace or line-ending changes that hide in normal editors.
Frequently asked questions
Q. Is the diff line-based or character-based?
A. Line-based, like git diff. Two lines that differ by one character render as one removal and one addition rather than an inline highlight.
Q. How is whitespace handled?
A. Whitespace differences cause line mismatches. To ignore them, normalise both inputs (trim trailing spaces, convert tabs to spaces) before pasting.
Q. Will it work for very large files?
A. It runs in your browser, so performance depends on your machine. Tens of thousands of lines are usually fine; for huge files prefer git diff or diff -u from the command line.
Q. Does the comparison get sent to a server?
A. No. The diff runs locally in JavaScript, so confidential text never leaves the browser tab.