Visualize unified diffs and patch files with color-coded additions and deletions.
Enter a unified diff or patch file content.
See additions in green and deletions in red with line numbers.
Click through individual change hunks to review each section.
Diff / Patch Viewer converts unified diff text into a structured, color-coded view of each affected file and hunk. It distinguishes removed lines, added lines, and unchanged context while retaining the old and new line positions declared by each hunk header. The frequent mistake is pasting two ordinary source files and expecting a comparison. This viewer expects an existing unified diff or patch, including its line prefixes and hunk metadata.
A concrete input and expected output from the current implementation.
Input
--- a/greeting.txt +++ b/greeting.txt @@ -1 +1 @@ -Hello, world. +Hello, Codex.
Expected output
One file comparison with old path `a/greeting.txt` and new path `b/greeting.txt`. The single hunk marks `Hello, world.` as a deletion at old line 1 and `Hello, Codex.` as an addition at new line 1.
The hunk header declares one old line and one new line, both beginning at line 1. The minus-prefixed line is removed, and the plus-prefixed line replaces it.
The `---` and `+++` headers identify the old and new file paths. A header such as `@@ -12,3 +12,4 @@` says that the displayed hunk covers three lines beginning at old line 12 and four lines beginning at new line 12. Those ranges provide line positions; they are not lines of source code.
Within a hunk, a line beginning with `-` is a deletion, a line beginning with `+` is an addition, and a line beginning with one space is unchanged context. The file header `+++` is not an added source line because it occurs in the patch header. A `\ No newline at end of file` marker describes file termination rather than content.
No. Its input is already formatted unified diff or patch text. To compare two raw file versions, first produce a unified diff with a comparison tool, then paste that result here. The viewer is for interpreting the patch structure and changes, not for inferring changes from separate before and after documents.
No. Added lines are only the plus-prefixed lines introduced by the patch. The resulting file also retains context lines shown with a leading space and unchanged lines omitted from the patch entirely. Deleted lines do not remain in the new version, although the viewer displays them so the change can be reviewed.
The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
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