Text Diff Checker
Compare two blocks of text line by line and highlight what was added, removed and unchanged.
Processing: This tool runs entirely in your browser. Your input and any file you open stay on your device — nothing is uploaded to a server.
How to use the text diff checker
- Paste the original text on the left.
- Paste the changed text on the right.
- Read the result: green lines were added, red lines removed.
About this tool
A diff answers the question 'what changed?' without asking you to read both versions. This tool aligns the two texts using a longest-common-subsequence comparison — the same approach version-control systems use — so unchanged lines stay paired up and only the real edits are marked.
Line-level comparison is deliberate. Word-level diffs look precise but produce noise when a paragraph is rewritten; line diffs stay readable on configuration files, lists, logs and code, which is where most comparisons happen.
Common uses
- Checking what an editor changed in a draft.
- Comparing two configuration files.
- Spotting the difference between two exported lists.
Frequently asked questions
- Does it compare word by word?
- No, it compares line by line. A line with a single changed word shows as one removal and one addition.
- Can I compare files?
- Open the files in any editor and paste their contents. Nothing is uploaded either way.
Related tools
Remove Duplicate Lines
Remove repeated lines from a list, with options to sort, trim whitespace and ignore case.
JSON Formatter
Format, validate and minify JSON with clear error messages that point at the exact position.
Word Counter
Count words, characters, sentences, paragraphs and estimated reading time as you type.
Text Case Converter
Convert text between UPPERCASE, lowercase, Title Case, Sentence case, camelCase, snake_case and kebab-case.