Code Compare Online: Review Source Code Changes
Review two code versions side by side or as a unified patch without uploading them.
Comparison content is processed in this browser and is not uploaded to DiffPeek.
Free source code comparison tool
Use this code compare tool for two versions of JavaScript, Python, Java, C#, SQL, configuration files, or any other text-based source code. The side-by-side view keeps original text on the left and revised code on the right. Added and removed lines appear with word-level or character-level edits so a small change is easier to review.
Ignore whitespace during refactors, hide unchanged context, and navigate each change. Select a changed row to edit the browser-side copy or merge it in either direction, then undo, redo, or export a unified diff. The tool does not write the original source file or perform a three-way merge.
How to compare and merge code
- Paste or open the original file on the left and the updated file on the right.
- Click Compare, then choose Split for a side-by-side view or Unified for patch-style text comparison.
- Turn on Ignore whitespace when formatting changes would hide the functional edits you want to inspect.
- Select a changed row before using a merge control. Each merge copies only that change, and Undo can reverse it.
- Download the chosen side or export a
.difffile for another code review workflow.
When this diff tool is useful
Code Compare is useful for checking a copied function, reviewing generated configuration, validating a small refactor, or comparing text code when a repository is unavailable. Green additions show code found only in the revised side; red deletions show code found only in the original. The inline highlight identifies the closest word or character edits inside paired lines.
Try a small function review
Open the JavaScript example to inspect a new optional parameter, an extracted local variable, a conditional return, and an updated call site. Review with whitespace ignored and then enabled to see how matching changes.
DiffPeek compares source as text. It does not parse an abstract syntax tree, run a formatter or linter, execute the code, understand renamed symbols, or connect to Git. Patch export retains the exact visible text.
Local comparison and supported file types
The comparison runs locally in your browser, and the source is not uploaded to DiffPeek. Any file type that can be decoded as supported text can be reviewed, but syntax highlighting is not currently applied; colors represent diff status rather than programming-language tokens. For a binary file or a complete directory, use the dedicated file or folder comparison tools instead.
Read the source comparison and patch workflow guide, review an entire repository with the Folder Diff Checker, compare structured configuration with JSON Compare, or open two files in the File Diff Checker.