Text difference checker
Runs in your browserNothing is uploadedThis runs entirely in your browser. Nothing is uploaded.
Paste two versions and see which lines were added, removed or replaced — and, inside a replaced line, which words actually changed. It all runs in the page, so contract drafts and internal config files can be compared without leaving your machine.
Original text
New text
Comparison rules and view
Comparison rules
Layout
Paste text into A and B and the differences appear here.
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Highlights
- Changes inside a line are marked
- On top of the line-level comparison, every replaced line is compared again at word level, so only the part that changed is highlighted. Latin words and numbers are kept whole and everything else is split per character, which also makes it work for Japanese.
- Text is never uploaded
- The comparison happens entirely in your browser and nothing you paste is sent anywhere, so contract drafts and internal config files are fine to compare.
- Symbols as well as colour
- Additions carry a "+" and an underline, removals a "−" and a strike-through, so the diff stays readable in greyscale, in print, and for anyone who cannot rely on the red/green distinction.
How to use it
Paste both versions
The "before" text goes in A, the "after" text in B. The sample button fills both with two drafts of a contract if you want to see it working first.
Read the diff
The comparison runs as soon as both sides have text. Added lines carry a "+" and an underline, removed lines a "−" and a strike-through, and inside a replaced line the changed words are marked. Line counts and a similarity figure sit above the sheet.
Adjust the rules, or take the patch
Open "Comparison rules and view" to ignore whitespace or case, and to switch between the side-by-side and unified layouts. "Copy unified diff" puts the result on the clipboard in the format git and patch read.
Reading the result
- Line-level versus word-level: what is the difference?
- The line pass decides which lines were added, removed or replaced. The word pass looks inside a replaced line and marks the words that moved. This tool runs both and layers the word marks on top of the line verdict.
- Why does every single line show as changed?
- Usually line endings. Windows writes CRLF and macOS/Linux writes LF, so two copies of identical text differ on every line as far as a byte comparison is concerned. This tool unifies line endings before comparing, so that cause is already handled. If everything still shows as changed, look for tabs swapped for spaces, or an encoding conversion that introduced full-width spaces.
- What does the similarity percentage measure?
- Twice the number of unchanged lines, divided by the two line totals. Identical texts score 100%, texts with no line in common score 0%. It is a line-level figure, so small edits within a line barely move it.
- How far does "ignore whitespace" go?
- It strips every space, full-width space and tab from a line before deciding whether the two lines match — useful when only the indentation was reworked. If you only want to forgive stray spaces at the end of a line, use "ignore trailing spaces" instead. Either way the options only affect matching; what you see on screen is the text exactly as you pasted it.
Questions
- Is there a size limit?
- 5,000 lines per side. Above that, the tool stops with a warning instead of comparing only part of the input. For anything larger, use git diff or a similar command-line tool.
- Is my text stored?
- No. Everything happens in the page and nothing is sent to a server. Close the tab and it is gone.
- What is the unified diff for?
- It is the standard "--- / +++ / @@" format that git and patch understand, with three lines of context around each change. Copy it into a review comment, or save it as a patch file.
- Can I compare Word or PDF files directly?
- No — this compares pasted text, so extract the text first. Formatting differences such as bold or colour are not part of the comparison.
- Side-by-side or unified?
- Side by side is better for checking which old line became which new one. Unified fits a narrow screen and reads top to bottom when you just want to walk through the changes. The underlying comparison is identical.
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