Text Diff Checker, Compare Two Texts Online
Paste two versions of any text and see exactly which lines were added, removed, or changed. Built for developers reviewing config changes, writers comparing drafts, and anyone diffing copied-and-pasted content.
How to use
- Paste the original text into the first box.
- Paste the changed version into the second box.
- Optionally tick the AI enhancement to get a plain-English summary of what changed.
- Click Run to see a unified diff with additions and deletions marked.
A diff is a line-by-line comparison of two texts that shows the minimal set of changes needed to turn one into the other. It is the same algorithm family (longest common subsequence) that powers git diff, code review tools, and document version history.
Unified diff output marks removed lines with a leading minus and added lines with a plus, with a few lines of unchanged context around each change so you can locate it in the original. This is far more reliable than eyeballing two documents side by side, a single changed character in a 500-line config is trivially visible in a diff and practically invisible to the naked eye.
Common uses: verifying what a teammate actually changed in an .env or YAML file, checking that a generated document matches its previous version, comparing API responses before and after a deploy, and reviewing edits to legal or marketing copy. The optional AI enhancement reads the raw diff and writes the kind of summary a reviewer would leave on a pull request, useful when the diff is long and you want the intent, not just the lines. Whitespace matters in diffs: a line that only changed its trailing spaces still counts as changed, which is a common source of noisy diffs from editors that trim whitespace on save.
Examples
Input: Original: 'timeout: 30', Changed: 'timeout: 60'
Output: - timeout: 30
+ timeout: 60Input: Original: two config keys, Changed: same two keys plus 'retries: 3'
Output: timeout: 60
debug: false
+ retries: 3Frequently asked questions
Is my text stored when I use this diff tool?
No. Anonymous runs are stateless, the two texts are compared server-side and the result returned. Nothing is written to disk or logged. Signed-in users get an optional history of their last 50 runs, which they can delete at any time.
Does the diff ignore whitespace?
No, whitespace changes are real changes and are shown. If your diff looks noisy, check whether an editor reformatted indentation or trailing spaces. Those show up as changed lines even though the visible text is identical.
What does the AI enhancement add?
It reads the computed diff and writes a short reviewer-style summary, what was added, removed, or reworded, and the apparent intent. You get 10 free AI enhancements per day without an account. The base diff is unlimited within normal rate limits.
Can I diff code with this?
Yes, it is line-based, so it works on code, configs, JSON, prose, or anything else made of lines. For syntax-aware refactoring diffs, a language-specific tool will do better, but for 'what changed between these two files' this is exactly the right tool.
Related tools
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