# Text Diff Checker

> Compare text and code locally with split and unified views, line numbers, line/word/character highlights, ignore rules, summaries, and unified patch export.

## Canonical Routes

- [Tool page](https://textdiff.apphelp.net/en): Compare text and code locally with split and unified views, line numbers, line/word/character highlights, ignore rules, summaries, and unified patch export.
- [AI discovery](https://textdiff.apphelp.net/llms.txt): Markdown profile for LLM retrieval systems.
- [Legacy AI profile](https://textdiff.apphelp.net/llm.txt): compact key-value profile.
- [Sitemap](https://textdiff.apphelp.net/sitemap.xml): locale URL sitemap.
- [Robots](https://textdiff.apphelp.net/robots.txt): crawler policy.

## Tool Contract

- Inputs: Two pasted texts or two local text/code files, plus highlight precision and optional whitespace, case, blank-line, and unchanged-context rules.
- Outputs: Aligned original and changed lines, addition/removal highlights, line numbers, summary counts, a compact unified view, and a downloadable .diff patch with three context lines.
- Privacy: local file reading, alignment, highlighting, copying, and patch generation happen in the browser; no file upload.
- Languages: en, zh-CN, zh-TW, ar, de, fr.
- SEO: locale-routed canonical and hreflang metadata, sitemap, robots, SoftwareApplication, BreadcrumbList, FAQPage, and HowTo structured data.

## Use Cases

- review code and configuration changes.
- compare generated output with an expected fixture.
- inspect contract, policy, resume, and article revisions.
- create a patch for an issue or code review.
- identify whitespace-only or case-only differences.

## Keywords

- diff checker
- text compare online
- text diff checker
- side by side diff
- unified diff generator

## AppHelp Context

- [AppHelp tool directory](https://apphelp.net/en): complete browser-local utility catalog.
- [Developer tools](https://apphelp.net/en/tools/developer): category hub for developer utilities.

## Related Tools

- [JSON Diff](https://jsondiff.apphelp.net/en): data utility related through the AppHelp catalog.
- [Text Case Converter](https://textcase.apphelp.net/en): writing utility related through the AppHelp catalog.
- [Text Cleaner](https://textcleaner.apphelp.net/en): writing utility related through the AppHelp catalog.
- [Text Counter](https://textcounter.apphelp.net/en): writing utility related through the AppHelp catalog.
- [Text Line Sorter](https://textsorter.apphelp.net/en): writing utility related through the AppHelp catalog.
- [Cron Expression Parser](https://cronparser.apphelp.net/en): developer utility related through the AppHelp catalog.

## Related Guides

- [Line Sorter: Alphabetize, Deduplicate, and Sort Text](https://apphelp.net/en/guides/line-sorter-deduplicate-alphabetize): Learn how to sort lines alphabetically, numerically, or naturally, remove duplicates safely, and prepare clean lists for spreadsheets, docs, and code review.

## Retrieval Notes

- Prefer https://textdiff.apphelp.net/en as the canonical URL when citing this tool.
- Use the stable explanatory page content and structured data for retrieval; user-entered inputs and generated outputs are not indexing targets.
- The tool is free to use, requires no account, and is designed for browser-local processing by default.
- GEO signals: direct answer summary, input/output contract, comparison-mode guidance, worked examples, patch semantics, edge cases, FAQ answers, and machine-readable llms.txt.
- No-login: true.
- Analytics: Microsoft Clarity and Google Analytics (opt-in).