Code Diff Checker
Compare two code snippets live with word-level highlighting — additions, deletions, an identical check, and a copy-ready unified patch.
About this ToolHow it works, benefits & use casesTap to collapse
The Code Diff Checker compares two snippets and shows exactly what changed between them. Paste your original code in the left panel and the modified version on the right, and it computes a line-by-line diff with intra-line word highlighting — so within a changed line you can see precisely which tokens were added or removed, not just that the whole line differs. A stats row tallies additions, deletions, unchanged lines, and the percentage of the file that changed, and an explicit banner tells you when the two snippets are byte-for-byte identical. You can toggle "Ignore whitespace" to skip indentation-only noise and "Ignore case" for case-insensitive comparison. The tool also generates a standard unified patch you can copy or download as a .patch file. Everything is computed in your browser as you type — no upload, no account, free to use.
How to Use
- 1Paste your starting code into the Original panel on the left (or click "Load example" to drop in a sample pair).
- 2Paste the changed code into the Modified panel on the right.
- 3Optionally tick "Ignore whitespace" to skip indentation-only changes, or "Ignore case" for case-insensitive matching.
- 4Click Compare to confirm — the diff, stats, and unified patch render live as you edit either side.
- 5Read the per-line diff with green additions and red deletions, then copy or download the unified patch as a .patch file.
Key Benefits
- Word-level highlighting pinpoints the exact tokens changed within a line
- Stats row counts additions, deletions, unchanged lines, and percent changed
- Explicit "identical" check confirms when two snippets match exactly
- Ignore-whitespace and ignore-case toggles cut down on irrelevant noise
- Generates a standard unified patch you can copy or download as .patch
- Old and new line numbers shown side by side for easy reference
- Runs entirely in the browser — code is never uploaded
Common Use Cases
- Reviewing a quick edit before committing it to version control
- Spotting unintended changes between two pasted versions of a function
- Comparing config files or JSON payloads to find the differing keys
- Generating a unified patch to share a change without a full git workflow
- Teaching how diff tools and unified-diff format work
Options
Leading / trailing indentation changes
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Yes. Beyond marking whole lines as added or removed, the checker runs a word-level diff on paired changed lines and highlights only the segments that actually differ. This makes small edits — a renamed variable or a changed string — easy to spot without scanning the entire line.
"Ignore whitespace" tells the diff engine to treat indentation and spacing changes as equal, so reformatting alone will not register as a difference. "Ignore case" makes the comparison case-insensitive, so "Value" and "value" are considered the same. Both can be enabled together and the diff recomputes instantly.