How does the diff checker work?

Formly uses the Longest Common Subsequence (LCS) algorithm to find the differences between two texts. It highlights additions in green and deletions in red, line by line.

Can I compare code files?

Yes — paste code from any language into both panels. The diff checker works on any plain text, including source code, JSON, markdown, and configuration files.

What does 'copy as patch' do?

Copying as patch gives you a unified diff format (like what git shows) that can be applied with the 'patch' command or viewed in diff-aware tools.

Is there a size limit?

No — the diff checker works with text of any length in the browser without sending data to servers.

All Tools

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Diff Checker

Free to Use

Compare two texts and see exactly what changed — added lines in green, removed lines in red. Uses LCS algorithm for accurate diffing.

Original

Modified

Frequently Asked Questions

Is this diff checker free?›

Yes, completely free with no account, no ads, and no usage limits.

What algorithm does it use?›

It uses the Longest Common Subsequence (LCS) algorithm — the same approach used by Unix diff and Git. This produces the minimal set of changes between two texts rather than a naive line-by-line comparison.

How accurate is the comparison?›

The LCS diff is exact: every line marked as added or removed is genuinely different. The comparison is case-sensitive and whitespace-sensitive by default, matching what a developer would expect from a code diff.

What are common use cases?›

Comparing two versions of a document, spotting changes in contract text, reviewing code snippets, debugging config file differences, and checking whether two JSON or CSV files are identical.

Is my text data private?›

Yes. Comparison runs entirely in your browser — neither the original nor modified text is ever sent to a server.

What Is Text Diff Checker?

A text diff checker compares two text blocks side by side and highlights differences — added lines (green), removed lines (red), and unchanged lines. Formly's free diff checker performs character-level and line-level comparison, useful for comparing code versions, document revisions, contract changes, and any scenario where you need to see exactly what changed between two text versions.

Why Formly's Text Diff Checker Is the Best Free Option

✓Character-level diff — see exactly which characters changed, not just which lines.
✓Side-by-side and inline view modes.
✓Copy diff output for documentation or reporting.
✓Works for code, contracts, documents, and any text.
✓Free with no file size limits and no account required.

Free Alternative to Diffchecker.com, Text Compare

→Diffchecker.com: Diffchecker requires signup for file saves. Formly is instant with no account needed.

→Text Compare: Basic functionality only. Formly offers character-level diff with richer output.

Who Uses Text Diff Checker?

Developers

Compare code files or configuration changes when a proper diff tool isn't available.

Legal & contract teams

Identify changes between contract versions before signing.

Writers & editors

Compare revised document drafts to see what changed from the original.

Popular searches: text diff checker, compare two texts online, online diff tool, text comparison tool free, find differences between two texts, code diff online.

Looking for a detailed guide? Read our in-depth tutorial on using Text Diff Checker for professional results.

Read Guide →

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