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Text Diff
A Text Diff tool aligns two pieces of text and highlights inserted, deleted, and modified lines so you can review differences at a glance — implemented locally in your browser with a longest-common-subsequence diff.
Diff+0 −0
Original
Changed
Paste two pieces of text above to see them diffed line by line.
About Text Diff
Paste two versions of text into the left and right panes to see a unified diff highlighting changed lines. The algorithm runs in O(N*M) time where N and M are the line counts — fast for files of practical size. Nothing is uploaded; both inputs live only in your tab.
What Text Diff does
- Side-by-side panes with line-level diff highlighting
- Inserted, deleted, and modified lines color-coded
- Longest-common-subsequence algorithm — same family Git uses
- Handles files up to several thousand lines per side
- Both inputs stay in your tab — nothing uploaded
When to reach for Text Diff
- Reviewing what changed between two versions of a config file
- Comparing an expected API response to the actual one
- Spot-checking what an AI rewrite changed in your prose
- Auditing the diff between two prompt versions while iterating
How to use Text Diff
- 01
Paste version A
Paste the original text into the left pane.
- 02
Paste version B
Paste the changed text into the right pane.
- 03
Read the diff
Inserted lines are green, deleted lines are red, modified lines highlight the changed run inline.
When to use Text Diff vs alternatives
| Alternative | Use Text Diff when… | Use the alternative when… |
|---|---|---|
| `git diff` in the terminal | the two versions are not in a Git repo — e.g., pasted from chat, email, or two browser tabs. | you are already in a repo. |
| diffchecker.com or similar | the content is sensitive and cannot be uploaded to a third party. | you want shareable diff URLs. |
Frequently asked questions
What algorithm does the diff use?
A longest-common-subsequence diff at line granularity — the same family of algorithm Git uses. It produces intuitive diffs and is fast enough for files up to several thousand lines per side.
Can I diff JSON or code?
Yes — paste either side as JSON, JavaScript, or any text. For best results with JSON, format both sides first using the JSON Formatter so line breaks line up.
Does this work for binary files?
No. Diff tools operate on text. Drop a binary file and you'll see meaningless byte-level output.