Text Compare & Diff Checker
Paste two texts, hit compare, and instantly see every addition, deletion, and unchanged line highlighted side by side.
descriptionOriginal Text
edit_noteModified Text
How to Compare Two Texts Online
1. Paste Your Texts
Paste the original text in the left panel and the modified version in the right panel. Works with code, essays, documents, and more.
2. Hit Compare
Click the Compare button to run a line-by-line diff. Toggle options like ignore whitespace or case-insensitive mode for flexible matching.
3. Review Differences
Additions appear in green, deletions in red. View stats for lines added, removed, and the overall similarity percentage.
What Is a Text Diff Checker?
A text diff checker is a tool that compares two pieces of text and highlights the differences between them. It works by analyzing each line of both texts and classifying them as added, removed, or unchanged. This is incredibly useful for developers comparing code versions, writers tracking document revisions, students checking essay edits, or anyone who needs to quickly spot what changed between two text versions.
Our free online text compare tool uses a longest common subsequence (LCS) algorithm to produce accurate, line-by-line diffs entirely in your browser. No data is ever sent to a server, making it safe for sensitive or confidential content.
Common Use Cases for Text Comparison
Code Review
Compare two versions of source code to spot bugs, refactors, or unauthorized changes.
Document Revisions
Track changes between contract drafts, legal documents, or essay revisions.
Translation QA
Compare original and translated texts side by side to verify accuracy.
Config File Diffs
Quickly spot differences in configuration files, .env files, or YAML configs.
Frequently Asked Questions
How does the text diff checker work?expand_more
Our diff checker uses a longest common subsequence (LCS) algorithm to compare texts line by line. It identifies which lines were added, removed, or remained unchanged, then highlights them with green (additions) and red (deletions) backgrounds.
Is my text data safe and private?expand_more
Absolutely. All text comparison happens entirely in your browser using JavaScript. No text is sent to any server, stored, or logged. Your data stays on your device at all times.
Can I compare code with this tool?expand_more
Yes! This tool works great for comparing source code, configuration files, scripts, and any other plain text. Use the "Ignore Whitespace" toggle to focus on meaningful changes and ignore formatting differences.
What does the similarity percentage mean?expand_more
The similarity percentage indicates how much of the modified text matches the original. A 100% similarity means the texts are identical, while 0% means they share no common lines.
Can I compare texts with different letter casing?expand_more
Yes. Enable the "Case Insensitive" toggle to treat uppercase and lowercase letters as the same. This is useful when you only care about content differences, not formatting.
What is the maximum text length I can compare?expand_more
Since everything runs in your browser, there is no server-imposed limit. However, very large texts (over 50,000 lines) may cause your browser to slow down. For best performance, keep comparisons under 10,000 lines.
How do I copy or share the diff results?expand_more
Click the "Copy Diff Result" button above the diff output. This copies the entire diff in a standard unified format (with + and - prefixes) that you can paste anywhere.
Does this tool support file uploads?expand_more
Currently, you paste text directly into the two panels. To compare files, open them in a text editor, copy the contents, and paste them into the Original and Modified text areas.