Free Text Diff Checker
Compare two versions of any text side by side. Instantly see every added, removed, and unchanged word highlighted — perfect for proofreading, editing, and version control.
Comparison Tool
What Is Text Diffing and When Should You Use It?
Text diffing is the process of comparing two versions of text and identifying exactly what changed between them. This tool uses the Longest Common Subsequence (LCS) algorithm — the same mathematical approach used by version control systems like Git — to pinpoint every added and removed word with precision.
Proofreading and editing: Paste a draft and its revised version to instantly see which sentences were rewritten, which words were cut, and which phrases were added — without reading both versions line by line.
Legal document review: Compare contract drafts to catch unauthorized changes, spot deleted clauses, or verify that only the agreed-upon edits made it into the final version.
Academic writing: Track changes between essay drafts, compare paraphrased passages against the original, or verify that suggested revisions were incorporated correctly.
Content and copywriting: Check the difference between a client's brief and the delivered copy, or compare two headline variations before publishing.
Version control without code: Any workflow where two people edit the same document — meeting notes, policy documents, product specs — benefits from a fast, readable word-level diff.
How to Use the Text Diff Checker
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Paste or type your original text into the left panel.
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Paste or type the revised version into the right panel.
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Differences appear instantly: green highlights show additions, red shows deletions.
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Use the summary bar to see total words added, removed, and unchanged at a glance.
Frequently Asked Questions
What is a text diff checker?
A text diff checker compares two pieces of text and highlights every difference — added words, removed words, and unchanged content — making it easy to spot edits between versions. This tool uses the Longest Common Subsequence (LCS) algorithm to find the largest set of words that appear in both texts in the same order, then marks everything outside that sequence as either added or removed. The result is a word-level diff: each individual word is classified rather than each line or character.
Is my text kept private?
Your text stays completely private because all comparison runs in your browser using JavaScript — nothing is ever sent to our servers. There is no account, no login, and no data stored anywhere outside your device. The moment you close or refresh the tab, your text is gone. This makes the tool safe for sensitive content: confidential contracts, personal writing, internal documents, or anything you would not want to upload to an external service.
Can I compare text in any language?
Yes. The diff checker tokenizes text by splitting on whitespace, which works with any language that separates words with spaces — including English, Ukrainian, German, French, Spanish, Italian, Dutch, Portuguese, Swedish, Polish, and Korean. The tool handles Unicode correctly, so accented characters, Cyrillic script, and non-Latin alphabets all diff accurately. Note that languages without whitespace word boundaries, such as Chinese or Japanese, will treat runs of text as single tokens rather than individual words.
What do the colors mean?
Green highlighted words were added in the revised text — they appear in the right panel but not in the original. Red highlighted words with a strikethrough were removed from the original — they appear in the left panel but not in the revised version. Gray words are unchanged and appear in both texts in the same position. The summary bar below the panels shows the exact count of added, removed, and unchanged words so you can gauge the scale of edits at a glance.
Is this tool free?
Completely free with no registration required, no usage limits, and no premium tier. There are no file size caps and no restrictions on how often you use it. The tool is funded by non-intrusive display advertising and will remain free to use without an account.