Diff checker terms, in plain words
A diff checker lines up two versions of the same text and marks what was removed, added or edited, so if a client sends back homepage copy where “grows” became “scales” and the price moved from $29 to $39 (example), you see those two words highlighted instead of re-reading the whole page.
Copy changes hands many times on a client project: your draft, their edits in an email, a colleague’s tidy-up, the version that finally goes live. These words describe what the checker shows when you put two of those versions side by side.
- V1 and V2
- The older text and the newer text. Put the version the client last approved, or the one you sent, in V1, and the version you just received in V2. Everything is described as a change from V1 to V2.
- Removed line
- A line that is in V1 and has no close match in V2. It is shown in red, marked with a dash and its V1 line number.
- Added line
- A line that only exists in V2, such as a new paragraph or bullet. It is shown in green with a plus sign and its V2 line number.
- Edited line
- A line that is still there but was reworded. Instead of showing it as one line removed and one added, the checker keeps the pair together and highlights only the words that moved, so a single changed price or name stands out.
- Words view
- The whole text as one flowing passage, with removed words struck through and added words underlined. Best for long paragraphs where the line breaks moved, such as blog posts and email drafts.
- Changes only
- Hides the long runs of untouched lines and keeps two lines of context around each change, so a 400-line page with three edits fits on one screen.
- Change report
- A plain-text list of every change with line numbers, where removed words are wrapped in [- -] and added words in {+ +}. It pastes cleanly into an email, a ticket or a change request.
Sample copy changes run through the diff checker
These are made-up snippets of client copy, not real projects. Each row runs through the same diff code as the checker above, so the counts are exactly what you would see if you pasted the same two versions.
| Example | Lines edited | Lines removed | Lines added | Words out | Words in | Result |
|---|---|---|---|---|---|---|
| Example: homepage headline, one word swapped | 1 | 0 | 0 | 1 | 1 | Different |
| Example: pricing page, price and plan name edited | 2 | 0 | 0 | 2 | 2 | Different |
| Example: about page, a new paragraph added | 0 | 0 | 1 | 0 | 8 | Different |
| Example: legal footer, a line removed | 0 | 1 | 0 | 3 | 0 | Different |
| Example: button labels, only capitals changed | 1 | 1 | 1 | 5 | 5 | Different |
| Example: same labels, case ignored | 0 | 0 | 0 | 0 | 0 | Match |
| Example: product blurb, rewritten from scratch | 0 | 1 | 1 | 6 | 6 | Different |
Where a text diff checker can mislead you
The diff checker sees characters, not meaning
Swapping “will” for “may” is one word in the count but can change a promise on a pricing page. A small number of changed words does not mean a small change. Read every highlighted word before you approve it or send it on.
Formatting does not travel through a text diff checker
Bold, links, headings and colours are lost when you copy text out of a document or a web page. If the client changed a link target or made a line a heading, this tool will not show it. For the look of a page, compare screenshots instead.
Hidden characters can show up as changes
Curly and straight quotes, non-breaking spaces and different dashes look the same on screen but are different characters. If a line shows as edited and you cannot see why, turn on “Ignore spacing” first, then look closely at the quotes and dashes.
Very large or very different texts are matched more roughly
When two texts share almost nothing, the checker stops searching for the smallest set of changes and shows the middle part as removed and re-added. The result is still correct, just less detailed, and the page tells you when that happens.
Questions about the diff checker
Does the diff checker upload or store my text?
No. The comparison runs in your browser tab, and nothing you paste is sent anywhere or saved. Closing or reloading the page clears both boxes, so it is safe for unreleased copy, contracts and client drafts.
Which should go first in the diff checker, the old or the new version?
Put the older or approved version in V1 and the newer one in V2. If you get it the wrong way round, use the swap button: added and removed simply trade places.
Can the diff checker ignore capital letters and extra spaces?
Yes. Turn on “Ignore case” to treat “Book A Table” and “Book a table” as the same, and “Ignore spacing” to skip doubled spaces, tabs and trailing spaces. Both are off by default, because a client may care about either.
How do I send the diff checker result to a client or teammate?
Use “Copy change report” for a plain-text list with line numbers, or “Download .txt” to attach it. The report marks removed words as [-old-] and added words as {+new+}, which reads well in any email program.
Can the diff checker compare two PDFs or Word files?
Paste the text from each file and it works. For PDFs, the compare PDF tool reads both files on your device and tells you the page each change is on, which saves copying text out page by page.
Why does the diff checker show a whole line as removed and re-added?
When an old and a new line share very few words, pairing them would highlight almost everything. The checker shows them as one removed and one added line instead, which is easier to read when a sentence was rewritten from scratch.
What is a diff checker useful for on client projects?
Checking what a client actually changed when they reply with “a few tweaks”, confirming that the copy going live matches the approved version, and turning a pasted email full of edits into a clear list you can price as a change request.