Code Diff Viewer: Free Online Code & Text Comparison Tool — How-To Guide

Try it free: Code Diff Viewer

What the tool does

The Code Diff Viewer lets you compare two text or code snippets right in your browser — no software to install, no account to create, no files uploaded anywhere. Paste "version A" on one side and "version B" on the other, and the tool highlights exactly what changed: added lines, removed lines, and even word-level differences inside lines that otherwise look identical.

It's built for everyday comparison jobs: reviewing a code change before committing, spotting edits between two drafts of a document, comparing log outputs, or checking whether a config file was altered. Alongside side-by-side and inline diff views, it can export a readable .txt report of the differences, plus an optional unified .patch file for developer workflows.

Step-by-step: how to use it

1. Open the tool. Go to the Code Diff Viewer page. Everything loads instantly — there's nothing to sign into.
2. Paste the original text. Put the first version of your code or text into the left/original input area.
3. Paste the modified text. Put the second version into the right/modified input area.
4. Review the diff. The tool immediately shows the comparison. Switch between side-by-side view (both versions next to each other, great on wide screens) and inline view (changes shown in a single combined panel) — pick whichever reads better for your content.
5. Drill into word-level highlights. Lines that were edited — not added or removed — show exactly which words changed, so you don't have to eyeball a whole line to find a one-character fix.
6. Copy or download the result. Export the diff as a readable .txt report to share with a colleague, or as a unified .patch file if your workflow needs a standard patch format. You can also reset and start a fresh comparison.

Practical tips

• Paste, don't retype. Diff tools only catch what you give them. Copy each version directly from the source (your editor, a terminal, a document) so you compare the real text, including whitespace.
• Check whitespace before you panic. A diff that flags every line as changed usually means one version has trailing spaces or different line endings. This is almost always a formatting artifact, not a real change.
• Use the .patch export for handoffs. If you're sending the diff to a developer, the unified patch export gives them something they can apply with standard tooling instead of a screenshot or pasted text.
• Compare small chunks for big files. If a file is huge, comparing only the section you care about makes the result far easier to scan than a full-file diff with thousands of lines.

FAQ

Q: Do I need to install anything or create an account?
A: No. The Code Diff Viewer runs entirely in your browser. Open the page, paste your text, and compare.

Q: Is my code uploaded to a server?
A: No. The comparison runs locally in your browser — your snippets, drafts, and logs never leave your device.

Q: Can I compare something other than code?
A: Yes. It works with any text: articles, contracts, configuration files, log output, lists — anything you can paste.

Q: What export formats are available?
A: A readable .txt report of the differences by default, with an optional unified .patch export for developer workflows.

Privacy note

The Code Diff Viewer runs 100% in your browser — your text is never uploaded, stored, or sent anywhere. That's what makes it safe for sensitive snippets, internal configs, and drafts: nothing leaves the device you're working on.

Compare your code free at toolsfam.com/tools/code-diff-viewer.