Diff Checker

Compare two blocks of text side-by-side with line-level and character-level diff highlighting. Everything runs in your browser — no data is ever sent to a server.

Private & Secure 100% Client-Side Zero Tracking

Enter text in both fields and click Compare to see the diff.

What Is a Diff Checker?

A diff checker (also known as a text compare tool or text diff tool) identifies the differences between two blocks of text. It highlights lines that have been added, removed, or changed, making it easy to compare code, documents, configurations, or any text content.

How This Diff Tool Works

This tool uses a Longest Common Subsequence (LCS) algorithm to compute the optimal diff between your original and modified texts. It identifies:

  • Added lines — lines present only in the modified text (shown in green)
  • Removed lines — lines present only in the original text (shown in red)
  • Changed lines — lines that exist in both but differ, with character-level highlighting showing exactly what changed
  • Unchanged lines — identical lines in both texts (shown in gray)

Use Cases for Text Comparison

  • Code review — compare two versions of source code to spot changes before merging
  • Version control — visualize what changed between commits, branches, or file revisions
  • Configuration auditing — compare server configs, environment files, or deployment manifests
  • Document editing — see what changed between draft revisions of articles, contracts, or documentation
  • Debugging — compare expected vs. actual output, logs, or API responses

Side-by-Side vs. Inline Mode

This diff checker offers two viewing modes. Side-by-side mode places the original and modified texts in parallel columns with aligned line numbers, similar to GitHub's split view. Inline mode displays all changes in a single column with +/- prefixes, similar to the unified diff format used by Git and other version control systems.

Privacy and Security

All text comparison happens entirely in your browser using JavaScript. No text is transmitted to any server, stored in any database, or logged anywhere. Your data stays on your device. This makes SecureBin's Diff Checker ideal for comparing sensitive code, credentials, configuration files, or any private content.