Text Diff

Compare two texts side by side with line-by-line diff highlighting. See added, removed, and unchanged lines with similarity score.

Compare two texts side by side
Text 1 (Original)
Text 2 (Modified)

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APIPOST /api/v1/text/diff
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Try also: Text Analyzer
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Key Features

100% Free

No registration required, unlimited checks

Instant Results

Real-time analysis with detailed output

REST API Access

Integrate into your workflow via API

Accurate Data

Live queries to authoritative sources

What is Text Diff?

The text diff tool compares two blocks of text side by side and highlights every difference with color-coded line-by-line analysis. Added lines are shown in green, removed lines in red, and unchanged lines are dimmed for focus. The tool also calculates an overall similarity score (0-100%) to quantify how alike the two texts are.

This free online text comparison tool is essential for developers comparing code versions without a full Git setup, editors tracking changes between document revisions, teachers checking student submissions for plagiarism or unauthorized collaboration, translators verifying that source and target texts have matching structure, QA teams comparing expected vs actual output in test results, and anyone who needs to quickly find what changed between two versions of any text.

How to Use

  1. 1Paste the original text in the left panel (the 'before' version)
  2. 2Paste the modified text in the right panel (the 'after' version)
  3. 3View highlighted differences: green = added lines, red = removed lines, dimmed = unchanged
  4. 4Check the similarity score (0-100%) and counts of added, removed, and unchanged lines
  5. 5Use the results to review changes, verify edits, or identify unintended modifications

Who Uses This

System Administrators

Monitor and troubleshoot infrastructure

Developers

Debug network issues and integrate via API

SEO Specialists

Verify domain configuration and performance

Security Analysts

Audit and assess network security

Frequently Asked Questions

How do I compare two texts online?
Paste the original text in the left panel and the modified version in the right panel. The tool instantly performs a line-by-line comparison and highlights every difference: green lines were added in the new version, red lines were removed from the original, and dimmed lines are unchanged. You also get a similarity percentage and counts of changes. This works for any text — articles, code, configuration files, legal documents, translations.
What does the similarity score mean?
The similarity score is a percentage showing how alike the two texts are, calculated from the ratio of unchanged content to total content. 100% means the texts are identical — no differences found. 90-99% means minor edits (typo fixes, small additions). 50-89% means significant changes while retaining core structure. Below 50% means the texts are mostly different. 0% means completely different content with no matching lines.
Can I compare source code with this tool?
Yes — the text diff tool works with any plain text including source code in any programming language, configuration files (YAML, JSON, TOML, INI), SQL queries, Markdown documents, CSV data, and more. It compares line by line just like 'git diff' or VS Code's built-in diff viewer. This is useful for comparing code changes without a full Git setup, reviewing configuration differences between environments, and comparing API response outputs.
How does line-by-line diff work?
The tool uses a diff algorithm (similar to the Unix diff command and Git's diff engine) that finds the Longest Common Subsequence (LCS) between the two texts. Lines present in both texts in the same order are marked as unchanged. Lines in the left text but not the right are marked as removed (red). Lines in the right text but not the left are marked as added (green). The algorithm is optimized to produce the minimal set of changes needed to transform the original into the modified version.
Can I compare documents with different formatting?
The tool compares plain text content only, so formatting differences (bold, italic, font size) in rich text documents are not detected. If you paste text from Word or Google Docs, only the text content is compared, not the formatting. For comparing whitespace differences (spaces, tabs, line endings), the tool treats each line as a unit — lines that differ only in trailing whitespace may show as changed. For code comparison where whitespace matters (Python), this behavior is correct.

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API Endpoint

POST /api/v1/text/diff
View Documentation