How to review a Claude Code diff when you aren't a developer

You can review Claude Code's changes without reading code fluently. A diff, the list of lines added and removed in each file, answers most of the questions a business owner or marketer needs to ask: did it change only the files I expected, about as many lines as the task needed, and none of the text I care about by accident? Combine that with a look at the changed page on a staging copy, and you'll catch most of the problems that matter to customers.

What you can't do as a non-developer is judge whether code is secure, efficient or correct in every case. That's where a developer, an automated check or Claude Code's own review commands come in. This guide shows where to find the diff in each Claude Code surface, a short review routine, the red flags that mean stop, and when to hand a change to someone technical, as of October 2026.

What a diff is, in plain terms

A diff compares two versions of the same files. For each file that changed, it shows the lines that were removed (usually red, often marked with a minus sign) and the lines that were added (usually green, with a plus sign). Unchanged lines around them give context. A summary such as "+12 -1" means twelve lines added and one removed.

On GitHub, the pull request review screen lets you switch between a unified view, with old and new lines stacked, and a split view, with old on the left and new on the right. Some people find split view easier to follow. GitHub also lets you hide whitespace changes, which removes noise when only indentation moved.

Where to see Claude Code's changes

One detail from Anthropic's docs: in the terminal's /diff, the per-turn views come from Claude's file edits, so a change Claude made through a shell command shows up only in the overall view of uncommitted changes, labeled Current. Check that view before you sign off.

A short review routine

1. Restate the task. Write down in one sentence what you asked for. Everything in the diff should serve that sentence.
2. Read the file list first. Before any lines, look at which files changed. Ask yourself whether each one belongs to the task. A footer fix shouldn't touch the checkout.
3. Check the size. A one-sentence change that adds 400 lines needs an explanation.
4. Read the text you care about. Scan added lines for prices, phone numbers, addresses, names, legal wording, page titles and links. Compare each against your source of truth.
5. Look at what was removed. Red lines are easy to skip. Make sure nothing you need disappeared: a tracking tag, a redirect, a disclaimer, a whole section.
6. Ask Claude to explain anything unclear. Prompt: Explain each changed file in one or two plain-English sentences, and tell me why each change was needed for this task.
7. See it in a browser. Open the changed pages on your local preview or staging copy, on mobile and desktop. Click the buttons. Submit the form with test data if it changed.
8. Decide. Approve, ask for changes, or hand it to a developer.

For changes that run across many pages, check more than the first one. When we rebuilt eseospace.com, a script replaced the wrong section and new posts carried the template post's text. The first page looked fine. The lesson we wrote down: check the second page a script produces, not just the first, and read the counts it reports.

Red flags worth stopping for

Let Claude review its own work, carefully

Claude Code includes review commands that give you a second opinion before a person signs off.

• /code-review reviews the current diff for correctness bugs. Anthropic's best-practices page says it runs "in a fresh subagent," a separate assistant that sees the diff without the reasoning that produced it. In the desktop app, findings appear as a card where you can step through them in the diff view.
• /security-review compares your branch with the main branch of the online copy (git calls it the origin remote) and looks for risks "like injection, auth issues, and data exposure." It only works when that remote is set up. Use it on any change to forms, logins or user input.
• Your own review prompt. To check scope against what you asked for: Use a subagent to review this diff against my original request. Report anything outside the task's scope and anything the request asked for that's missing. Report gaps, not style preferences.

A caution from Anthropic: a reviewer asked to find gaps "will usually report some, even when the work is sound." Don't chase every finding. Ask for the ones that affect correctness or the stated requirements. And none of this replaces a person's approval for what goes live. Our guide to writing an AI code review policy covers how teams split review between people and tools.

Look at the result, not just the code

The diff tells you what changed in the files. Only the page tells you what changed for visitors. Check on a staging or preview copy, never the live site. Our guide to setting up a staging copy covers each platform.

• View every changed page at a phone width and a desktop width.
• Click every changed link and button.
• Submit any changed form with test data and confirm the submission arrives where it should.
• Check the page title and description in the browser tab or page source if SEO text changed.

The desktop app's Browser pane can open a local preview of the site (a development server), so Claude can check its own changes and you can look in the same window. A broader routine is in our guide to a QA routine before every deploy.

Leaving feedback Claude can act on

• In the desktop app: click a line in the diff view to open a comment box, add comments on several lines, then submit them together. Claude reads the comments and makes the requested changes, which appear as a new diff.
• On GitHub: in Files changed, hover over a line and click the comment icon, then start a review. Your comments stay private until you submit the review, where you can approve it or request changes.
• In the terminal: describe the problem by file and line: In the footer file, the phone number on the added line is wrong. It should match docs/company-facts.md. Fix only that line.

Be specific about what's wrong and what right looks like. "This isn't right" starts another guessing round.

When to call a developer

Hand the change to someone technical when any of these are true:

• You can't explain in your own words why a file changed, even after Claude explains it.
• The change touches forms, checkout, payments, logins, user accounts or stored customer data.
• It adds a library, changes build or deploy settings, or edits server configuration.
• It changes redirects or URL structure on more than a handful of pages.
• Automated checks fail and the proposed fix disables a check rather than fixing the cause.

Automated gates help here too. A required pull request review on GitHub and an automated QA run, such as the setup in our guide to website QA with Claude Code in GitHub Actions, make sure no change merges without both a person and a check passing.

Conclusion

Reviewing a Claude Code diff as a non-developer comes down to a routine: read the file list, check the size, read every line of text you're responsible for, look at what was removed, ask Claude to explain anything unclear, and see the result in a browser on staging. Use /code-review and /security-review as extra eyes, and pass anything touching forms, money or security to a developer. Our guide to whether non-developers can use Claude Code covers where that line sits, and our piece on AI-generated versus human-edited work explains why the human step matters. If you'd like a review process and training set up for your team, our Claude Code consulting covers both. More guides are in our Claude Code Guide.

Frequently asked questions