Text Diff Checker
Compare two pieces of text and see exactly what changed, line by line and character by character. Nothing is uploaded.
Both texts are compared in this page. Nothing you paste is uploaded.
2 added · 2 removed · 1 unchanged
| 1 | − | the quick brown fox | |
| 1 | + | the quick red fox | |
| 2 | 2 | jumps over the lazy dog | |
| 3 | − | and keeps going | |
| 3 | + | then stops |
Two versions of the same paragraph, contract or configuration file are almost never different in the way you remember them being. This lays them side by side and marks every line that moved, arrived or left, and inside a line that was rewritten it marks the characters themselves — so a changed number in the middle of a long sentence is a highlighted number rather than a highlighted sentence. Both texts stay in this page: nothing is sent anywhere, which is the part that matters when the thing you are comparing is a contract or a key.
How it is calculated
unchanged −removed +added
The comparison finds the longest run of lines the two texts share and treats everything else as an insertion or a deletion, which is the same idea diff has used since the 1970s. The output above uses the unified marks: a space for a line both sides have, a minus for one only the original has, a plus for one only the new version has.
Source: POSIX diff — the unified format, where a line is prefixed with a space, a minus or a plus
Questions people ask
- Why is a small edit shown as a whole line removed and added?
- Because a line is the unit the comparison works in. When a removal is immediately followed by an addition the tool goes a level deeper and marks the characters that actually differ, so you see both: the line pair, and the part of it that moved.
- Does it handle different line endings?
- Yes. Windows, Unix and old Mac endings are all normalised before comparing, so a file that has merely travelled between systems does not show up as entirely rewritten.
- Is my text uploaded anywhere?
- No. The comparison runs in the page. That is the difference between this and pasting a contract into a site that processes it on a server, and it is the reason this tool exists in this form.
- Can I compare files rather than pasted text?
- Not yet — paste for now. The comparison itself does not care where the text came from, so reading a file is a smaller change than it sounds and is worth asking for.
- What does the unified view give me that the side by side does not?
- It is the form patches are written in, so it can be pasted into a review comment or an email and read by anyone who has seen a diff before. Side by side is easier to read; unified is easier to send.
Related tools
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URL Encoder and Decoder
Percent-encode text as you type, choosing whether you are escaping one value inside a URL or an address as a whole. Nothing is uploaded.
HTML Entity Encoder and Decoder
Escape text for HTML and read entities back, with the attribute case kept separate from the text case. Everything runs in your browser.
Found a problem, or want more?
A number that disagrees with its source is a defect, not a rounding preference.
What did you enter, what did the tool show, and what did you expect instead? If you have a source that disagrees with ours, a link to it is the most useful thing you can send.
Opens your mail app with the page and tool already filled in.