Diff Checker
Paste two blocks of text — or drop two files — and see every change lined up with numbered rows. Read it side by side, as a unified diff, or inline, and drill down to the exact word or character that moved. You can tell it to ignore case, whitespace or blank lines, collapse the untouched parts, and export the whole thing as a standard .diff patch. Everything runs inside your browser, so confidential code and contracts never leave your machine.
- Side-by-side, unified and inline views
- Numbered lines with word- or character-level highlighting
- Drag and drop a file onto either side
- Ignore case, whitespace or blank lines
- Collapse unchanged lines to focus on what moved
- Added, removed and similarity statistics
- Export a standard .diff patch or copy it
- 100% local — no data leaves your browser
How to use the Diff Checker
- 01
Add both texts
Paste into the two boxes, or drag a file onto either one.
- 02
Pick a view
Side by side, unified, or inline — plus word or character detail.
- 03
Tune the comparison
Ignore case, whitespace or blank lines so only real changes show.
- 04
Read or export
Green is added, red is removed. Copy or download the .diff patch.
Frequently asked questions
What is a diff checker?+
A diff checker compares two blocks of text and highlights exactly what changed between them. Additions appear in green, deletions in red, and matched lines stay neutral, so you can see at a glance what a rewrite, an edit or a code change actually did.
What is the difference between the side-by-side, unified and inline views?+
Side by side puts the original and the modified version in two numbered columns, which is easiest for reviewing edits. Unified stacks everything into one column with + and − markers, the same format Git and code reviews use. Inline merges both versions into a single flowing block, which reads well for prose where you want to see the old and new wording together.
What is the difference between word diff and character diff?+
Both compare line by line first, then look inside the lines that changed. Word detail highlights whole words, which keeps prose readable. Character detail highlights individual characters, which is better for catching a typo, a flipped digit or a single-character code change.
Can I compare two files instead of pasting text?+
Yes. Drag a file onto either box, or use the File button to browse. Any plain-text format works — .txt, .md, .json, .csv, .log, and source files like .js, .ts, .css or .html. The file is read locally in your browser and never uploaded.
What do the ignore options do?+
Ignore case treats Name and name as the same. Ignore whitespace collapses runs of spaces and tabs, so re-indented code stops showing up as a change. Ignore blank lines skips empty lines on both sides while keeping the original line numbers intact. Turn them on to strip out cosmetic noise and leave only meaningful differences.
What can I do with the .diff file?+
The download is a standard unified diff with @@ hunk headers and three lines of context. You can attach it to a ticket or pull request, share it as a review artefact, or apply it to a copy of the original with git apply or the patch command.
How is the similarity percentage calculated?+
It compares how many characters the two texts still have in common against their combined length. 100% means the texts are identical under your current ignore settings, and the number drops as more of the content differs.
Is my text private?+
Yes. The comparison runs entirely in your browser using client-side JavaScript. Nothing you paste or drop is sent to a server, logged, or stored anywhere.
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