Reviews are the contribution type most likely to make you re-rank the developers you think you know. The metric counts pull-request reviews submitted in public repositories — every time a user approves, requests changes, or submits a review comment on someone else's PR.

What GitHub counts

Submitting a review on a pull request (approve, request changes, or a comment review): +1 per review.
Plain inline comments outside a review, issue discussions, or mentoring in chat: not counted.
Reviews in private repositories: folded into private contributions.

Why this number matters more than it looks

Reviewing is the classic case of engineering work that's essential and invisible. A thorough review of a complex change can take longer than writing it — reading the diff, checking the edge cases, testing locally, writing feedback that lands well. None of that produces a commit under the reviewer's name. The author gets the commit and the PR; the reviewer gets… this number.

That's why review counts skew toward a specific profile: senior engineers and maintainers. As people grow in a codebase, their output shifts from writing changes to vetting them. A profile with a flattening commit curve and a steepening review curve isn't slowing down — it's a promotion, drawn as a chart.

Sheer volume has a mundane driver too: required-review workflows. In projects where every PR needs an approval, active maintainers accumulate thousands of reviews as a structural consequence of the process.

What it doesn't measure

Depth. A rubber-stamp "LGTM" and a forty-comment security review both count once. And it misses review-shaped work that never becomes a formal review — pairing, design docs, architectural pushback in the comments.

How commit-history.com tracks it

Monthly review contributions accumulated from account creation into the cumulative curve; the leaderboard ranks lifetime totals. Flip a few famous profiles to Reviews — the shape of the curve tells you when they stopped being mostly-author and became mostly-editor.

See it in action

Look up a profile and switch to Reviews, or compare an author-heavy and a reviewer-heavy developer — then check Total, which is where review-heavy engineers finally get full credit.