Compare two texts side-by-side. Highlights additions and deletions.
Compare two blocks of text side-by-side with highlighted additions and deletions. Powered by the Google diff-match-patch library. Ideal for comparing document versions.
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Spotting what changed when you have two versions and no version control — a contract returned with edits, two exports of the same data, a config file that works against one that does not. It answers "what is actually different here" far faster than reading both documents side by side.
Because line-based comparison treats a line as the unit — any change within it marks the whole line. It is the same behaviour as git diff. For prose this can look noisy, which is why keeping one sentence per line makes documents far easier to compare meaningfully.
No, comparison runs entirely in your browser. That matters here more than for most tools, since diffing usually involves two versions of something real — a contract, source code, customer data — and both would otherwise be leaving your machine simply to be compared.
Yes, Text Difference Checker is completely free. No signup, no account, and no watermark on outputs. A Pro tier is available for 100 AI ops/day and larger file sizes.
Text Difference Checker runs entirely in your browser. Your file is never uploaded — it is read, processed and saved locally, so it never reaches our servers or anyone else's. You can disconnect from the internet after the page loads and it still works.
Diff modes: Character mode shows every single character change. Word mode is best for prose and natural language. Line mode works best for code, JSON, and structured data — it highlights entire changed lines.
Algorithm: Uses the diff-match-patch library — the same algorithm used in Google Docs and many code editors. It finds the minimum edit distance between two texts using the Myers diff algorithm.
Similarity score: Calculated as (unchanged characters / total characters). 100% means identical, 0% means completely different.