Text Diff Checker
Compare two texts and highlight differences instantly online. Free text diff tool with line-by-line and word-by-word diff modes. No signup required.
Original
Modified
Related Tools
Markdown → HTML
Convert Markdown to clean HTML instantly. Supports GFM, tables, code blocks, and more.
Case Converter
Convert text to camelCase, PascalCase, snake_case, kebab-case, and more — all at once.
HTML → Markdown
Convert HTML to clean Markdown instantly. Supports headings, links, lists, tables, and code blocks.
Text diffing compares two versions of a document and identifies which lines or words were added, removed, or unchanged between them. The Myers diff algorithm (1986) underlies most diff implementations including Unix diff, Git's diff engine, and many code review tools. It finds the shortest edit script (minimum insertions and deletions) transforming one text into another.
Text comparison is essential in version control workflows, document review processes, and content management. Developers compare configuration file versions before deploying, technical writers compare document drafts, and content teams audit changes between CMS versions. Diff output is also the input format for patch files applied by git apply and patch.
This tool computes diffs using the diff JavaScript library (an implementation of the Myers algorithm), supporting both line-level and word-level comparison modes. Added lines are highlighted in green and removed lines in red, with a summary of total additions and deletions. The word mode is useful for prose editing where line boundaries are irrelevant.
Common Use Cases
Comparing configuration file versions
Before deploying a configuration change to NGINX, PostgreSQL's postgresql.conf, or a Kubernetes ConfigMap, engineers compare the new version against the current production config. A line-diff highlights exactly which directives changed, were added, or removed — providing a precise change summary for the deployment review and change management ticket.
Reviewing contract or policy document edits
Legal and compliance teams reviewing revised Terms of Service, privacy policies, or vendor contracts need to identify every changed sentence. Pasting the old and new versions into a text diff produces a word-level comparison that highlights exactly which phrases were altered, inserted, or removed — faster than manual reading and more reliable than Track Changes in Word.
Auditing CMS content changes before publishing
Content management platforms like Contentful, Sanity, and Prismic do not always provide a built-in diff view for draft versus published versions. Pasting the old and new content into a text diff tool lets editors verify that only the intended edits were made, catching accidental deletions or formatting changes before the revision goes live.
Comparing translation outputs from multiple LLMs
When evaluating multiple machine translation outputs or LLM-generated text variations for quality, diffing two candidate outputs at the word level reveals exactly where they diverge: different word choices, rephrased clauses, and structural changes. This is more informative than reading both texts in sequence when small differences are significant.
How to Use the Text Diff Checker
- Paste your original text in the left panel and the modified text in the right panel.
- Differences appear instantly — green for additions, red for removals.
- Use the Lines toggle for line-by-line comparison (best for code).
- Use the Words toggle for word-level differences (best for prose).
- Click Example to see a sample diff.