Find the edit, then check what it means
A text diff shows what changed between two versions. It does not tell you how important the change is. Adding “not” to “You may attend” changes the message completely, even though the edit is tiny.
Start with changes that affect what someone will do: numbers, dates, names, and words that reverse the meaning. Then check spaces and line breaks. Finish by reading the revised text from beginning to end, not just the highlighted parts.
The short messages below are made-up examples for this guide. You can load them from “Try an example” in the Text Diff Checker. Save any text already in the boxes before resetting them.
1. Separate an edited line from a new line
Original
Meet at 10:00. Use the north entrance.
Revised
Meet at 10:30. Use the north entrance. Please bring an umbrella.
This produces one changed line, one added line, no removed lines, and one unchanged line. The edited time appears in two rows—before and after—but counts as one change. The umbrella instruction is a new line, so it counts as an addition.
The practical takeaway is more useful than the count: the meeting is 30 minutes later, and there is something to bring. Turn on “Show unchanged lines” to confirm that the north entrance is still the meeting point.
The first line-number column refers to the original text; the second refers to the revised text. Adding a line shifts later numbers. A different line number does not, by itself, mean the wording changed.
2. If the lines look identical, check spaces and tabs
In this example, the entrance and time have not changed. The revised text has two spaces before “North” and a tab before “10:00.” To make them visible below, a space is shown as “·” and a tab as “→.”
Original, with spaces shown
Entrance:·North Time:·10:00
Revised, with spaces shown
Entrance:··North Time:→10:00
Load “Example 2: Spaces and tabs,” compare, and turn on “Show spaces and tabs” to reproduce this result. Both lines count as changed. The checker also displays full-width spaces as “□.” These are display markers only: they do not alter your input or the text produced by “Copy diff.”
Your text might already contain one of those symbols. Turn the option off to tell an actual symbol from a display marker. This option does not reveal every kind of invisible character.
Avoid deleting all spaces before your first comparison. Doing so can hide accidental deletions along with harmless spacing edits. Compare the originals first, then decide what needs cleaning up.
3. Distinguish line breaks and moves from wording changes
Splitting a sentence across two lines changes the units being compared, even if every word stays the same. Depending on how similar the lines are, the result may show a change and an addition, or a removal and additions. Moving a paragraph can also appear as removed and added text: this checker does not have a separate “moved” category.
Text wrapping to fit a narrow window is different from an actual line-break character. Some source documents insert line breaks when copied, however. If the result is unexpectedly fragmented, check where the pasted lines end before editing the wording.
Pattobako treats Windows (CRLF), Unix (LF), and CR-only line endings as equivalent. It does distinguish whether a final line break is present. Adding one after “A” is reported as an added empty second line.
What a diff cannot check for you
- Whether the revision is correct. A typo or factual error present in both versions will not be highlighted. Read numbers and changes in meaning in context.
- Whether the formatting matches. This checker compares the characters in its text boxes, not bold text, colors, images, or the layout of the source document.
- What the writer intended. Changed lines are paired by text similarity. Repeated passages and extensive rewrites can produce pairings different from the ones you expect.
For very long lines or large sets of changes, the checker may highlight a larger block instead of each small edit to limit processing work. If the result is hard to follow, keep the originals and compare matching sections separately.
“Copy diff” includes unchanged lines even when they are hidden on screen. It creates a review copy with before-and-after headers and “+” or “-” prefixes—not a finished draft. Copy from the revised input box if you need the revised text itself.
A quick check before you send
- Keep the originals and make sure the earlier and newer versions are in the right boxes.
- Review changes to numbers, dates, names, and words that reverse the meaning.
- Show unchanged lines to check the surrounding context.
- Check spacing and line breaks, then read the complete revised text.
Compare your two versions in the Text Diff Checker →
The comparison runs in your browser, without uploading your text. That does not remove copies from your clipboard or hide your screen on a shared device. Use a device appropriate for the sensitivity of the text.