A concise, actionable checklist of best practices for conducting and receiving effective code reviews to improve code quality, share knowledge, and ship reliable software.
1. Keep pull requests small and focused
Limit PRs to a single feature, bug fix, or refactor — ideally under 400 lines of changed code. Smaller PRs are reviewed faster, more thoroughly, and are easier to revert if something goes wrong.
2. Write a clear PR description before requesting review
Include the problem being solved, the approach taken, screenshots or test output where relevant, and any known trade-offs. Reviewers should never have to guess the intent of a change.
3. Review the intent, not just the syntax
Verify that the code actually solves the right problem and handles edge cases before focusing on style issues. Logic errors and incorrect assumptions are far more costly than minor formatting differences.
4. Use a checklist or PR template consistently
Standardize review criteria (tests written, docs updated, no secrets committed, migrations included) so nothing is forgotten. A shared template enforces completeness across the whole team.
5. Automate what machines can catch
Run linters, formatters, static analyzers, and CI tests automatically on every PR so reviewers can focus on logic, design, and correctness rather than style nits. Never make a human point out a missing semicolon.
6. Distinguish blocking issues from suggestions
Prefix comments clearly — e.g., 'blocker:', 'nit:', 'question:', or 'suggestion:' — so the author knows what must change before merging versus what is optional or just informational.
7. Respond to every comment before merging
Resolve each thread with a reply, a code change, or a reasoned rejection. Silently dismissing comments erodes trust and lets legitimate issues slip through.
8. Review your own code first
Before assigning reviewers, do a self-review in the diff view to catch typos, debug statements, and obvious mistakes. This shortens the review cycle and respects reviewers' time.
9. Give constructive, specific feedback
Replace vague comments like 'this is confusing' with concrete suggestions: 'Consider renaming `data` to `userInvoices` so the type is clear at the call site.' Specific feedback is actionable and less likely to feel personal.
10. Approve explicitly and promptly
Aim to complete first-pass reviews within one business day to avoid blocking teammates. Delayed reviews are a leading cause of context-switching costs and merge-conflict buildup.
11. Ensure adequate test coverage is part of the review
Verify that new logic is covered by unit or integration tests and that edge cases and failure paths are exercised. A PR without tests for new behavior should not be approved.
12. Never merge your own PR without another reviewer
At minimum, require one approval from a team member who did not write the code. Self-merging bypasses knowledge sharing and removes the safety net that catches blind spots.
13. Use code review to spread knowledge, not gatekeep
Rotate reviewers so no single person becomes a bottleneck, and treat reviews as teaching moments. Add inline links to docs, ADRs, or relevant prior art to help the whole team grow.
14. Close the feedback loop with post-merge learning
When a bug slips through a review, hold a brief retro to identify what the review missed and update your checklist or automated checks accordingly. Continuous improvement prevents repeat escapes.