How to Compare Text Online
FilePulp's Text Diff tool makes it easy to compare two versions of any text and see exactly what changed. Follow these steps:
- Paste your original text into the left panel. This is the "before" version of your text — the baseline you want to compare against.
- Paste your modified text into the right panel. This is the "after" version — the text with changes you want to identify.
- Choose your options. Select "Line by line" to compare entire lines, or "Word by word" to see character-level changes within each line. Toggle "Ignore case" or "Ignore whitespace" as needed.
- Click Compare. The diff output appears below in a side-by-side view, with additions highlighted in green and deletions in red.
The entire comparison runs locally in your browser. Your text is never uploaded to a server, stored, or transmitted anywhere. This makes it safe for comparing sensitive documents, contracts, source code, and anything else you want to keep private.
When to Use a Text Diff Tool
Code review
Compare two versions of a source file, configuration, or script to see what changed between revisions. The word-level highlighting pinpoints exactly which variables, values, or logic were modified — making it faster than reading through the entire file.
Document revision tracking
When collaborating on documents, paste the before and after versions to see every edit at a glance. This is useful for proofreading, reviewing contract changes, comparing drafts, or verifying that only the intended changes were made.
Contract comparison
Legal and business professionals can paste two versions of a contract, agreement, or policy to instantly identify what clauses were added, removed, or modified. The side-by-side view makes it easy to review changes before signing.
Data validation
Compare CSV exports, JSON responses, log files, or database dumps to quickly spot discrepancies. Toggle "Ignore whitespace" to focus on meaningful differences when formatting varies between sources.
Email and content comparison
Check how an email template, blog post, or marketing copy was revised. The line-by-line and word-by-word views make it easy to see subtle wording changes that might otherwise go unnoticed.
Understanding Diff Results
The diff output uses a color-coded side-by-side view to show you exactly what changed between the two texts. Here is what each color means:
Red / pink background — Lines or words that were removed from the original text. These appear in the left panel only.
Green background — Lines or words that were added in the modified text. These appear in the right panel only.
Dark red highlight — In word-by-word mode, the specific words within a changed line that were removed.
Dark green highlight — In word-by-word mode, the specific words within a changed line that were added.
Lines without any highlighting are unchanged — they appear identically on both sides. The summary bar above the diff output shows totals for added, removed, and unchanged lines, giving you a quick overview of how much changed.
Frequently Asked Questions
Is this text diff tool really free?
Yes, completely free with no limits. No sign-up, no hidden fees. Compare as many texts as you want, as often as you want.
Do you store or see my text?
No. All comparison happens locally in your browser using JavaScript. Your text is never sent to any server. We never see, store, or have access to anything you paste or type.
How does the diff algorithm work?
The tool uses a Longest Common Subsequence (LCS) algorithm to compute the minimal set of changes between the two texts. In line-by-line mode, it compares whole lines. In word-by-word mode, it additionally breaks changed lines into individual words and runs a second LCS pass to highlight the specific words that differ.
Can I compare code with this tool?
Yes. The tool works with any plain text including source code, configuration files, JSON, CSV, markdown, and more. Use the Ignore Whitespace toggle to focus on meaningful changes when comparing code.
What do the colors in the diff output mean?
Green highlights indicate additions — text present in the modified version but not the original. Red highlights indicate deletions — text present in the original but removed in the modified version. Within changed lines, darker highlighting pinpoints the specific words that differ.