Developer & Data

Diff Checker

Compare two texts or files line by line and word by word.

Compare two documents

Drop files onto either box, or paste text directly.

Result

Press Compare to see the differences.

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About Diff Checker

Offline text and code diff checker. Compare two documents side by side or inline, with line-level and word-level highlighting, whitespace and case options, similarity scoring and exportable patch output.

What it does

How to use it

  1. Paste the original text into the left box and the revised text into the right box.
  2. Choose the comparison options you need, such as ignoring case or trailing whitespace.
  3. Press Compare to see additions, deletions and modifications highlighted.
  4. Switch between side-by-side and inline views, or export a unified patch.

Diff Checker is one of 50 free tools from CRMTECH Solutions. See all Developer & Data tools or browse every tool.

Frequently asked questions

Does this send my text to a server?

No. The diff is computed in your browser using a Myers-style longest-common-subsequence algorithm written in plain JavaScript. Nothing is transmitted, so it is safe for confidential contracts, source code and log files.

What is the difference between line and word level?

Line level finds which lines were added, removed or changed. Word level then looks inside each changed pair of lines and highlights only the words that actually differ, which makes small edits in long paragraphs easy to spot.

Can I export the result?

Yes. Export a unified diff patch that git apply and patch understand, an HTML report you can email, or a plain-text side-by-side listing.

How large a file can it handle?

Comfortably up to around 20,000 lines per side. Beyond that the algorithm is still correct but the page will take a few seconds, so the tool warns you before starting.

What does the similarity percentage mean?

It is the proportion of lines that are identical in both documents, counted against the longer of the two. 100% means the documents match under your current comparison options.

Is Diff Checker free?

Yes. Diff Checker is free for everyone and needs no sign-up to use. An account is only needed to export, download or print, because every export is recorded.

Does it work on a phone?

Yes. It works in current versions of Chrome, Edge, Safari and Firefox on phones, tablets and computers, with nothing to install.