Ever stared at two versions of a document, trying to spot what's changed? Finding the subtle differences in code, contracts, or articles can be a frustrating and error-prone task. Our free Online Text Difference Checker (or "Diff Tool") instantly compares two blocks of text and highlights every addition and deletion, so you can see the changes in seconds.

How to Use Our Text Difference Checker

Finding the differences in your text is fast and automatic:

1. Paste your original text into the "Original Text" box on the left.
2. Paste the modified or new text into the "Changed Text" box on the right.
3. The comparison will appear instantly in the "Differences" box below, with additions in green and deletions in red.
4. Use the "Compare by" options to switch between highlighting differences by Characters, Words, or entire Lines.

Example: Comparing Code Snippets

This tool is invaluable for developers looking for small changes in code.

Original Text:

function greet(name) {
  return "Hello, " + name;
}

Changed Text:

function sayHello(name) {
  return "Hi there, " + name + "!";
}

The diff tool would clearly highlight that `greet` was changed to `sayHello`, `Hello` was changed to `Hi there`, and an exclamation point `!` was added at the end.

How Does a "Diff" Tool Work?

A "diff" tool (short for difference) uses a sophisticated algorithm to find the shortest sequence of insertions and deletions required to transform one block of text into another. The most famous of these is the Eugene W. Myers diff algorithm, which is highly efficient and forms the basis of many diff utilities, including the one used in `git`.

Our tool provides three levels of comparison to suit different needs:

• Characters: This is the most granular comparison. It is perfect for finding tiny changes like a single punctuation mark, a typo, or a changed letter.
• Words: This mode compares the text word by word. It's often the most readable option for prose, as it highlights entire words that have been added or removed, rather than every single character within them.
• Lines: This mode is ideal for code or log files. It compares the text line by line, highlighting entire lines that have been added, removed, or changed.

By visualizing these changes, diff tools save an immense amount of time and mental effort, allowing you to focus on the substance of the changes rather than hunting for them manually.

Frequently Asked Questions (FAQ)

Q1: Is the text I paste into this tool private and secure?

Yes, absolutely. This difference checker is a client-side tool. All the comparison logic is performed by JavaScript running in your own web browser. Your text is never sent over the internet or stored on our servers, making it completely safe and private.

Q2: Can I compare files instead of pasting text?

This simple online tool is designed for quickly comparing blocks of text that you can copy and paste. It does not support direct file uploads. For comparing entire files or folders, you would typically use a desktop application like WinMerge (for Windows), Meld (for Linux), or the comparison tools built into code editors like Visual Studio Code.

Q3: What does "diff" mean?

"Diff" is a common term in programming and software development that comes from the `diff` command-line utility, which has been used for decades to show the differences between files. The name has become a generic term for any tool or function that performs a text comparison.