Remote teams face a decision that office teams rarely think about: how code reviews should happen when everyone isn’t online at the same time.

Should reviewers and authors meet live to walk through changes together? Or should reviews happen asynchronously via pull requests and comments, without needing to schedule?

This choice affects more than team preference. It shapes how fast code moves to production, how developers protect focus time, and how well teams collaborate across time zones. 

For remote engineering teams, choosing the right review model can remove friction or quietly slow everything down.  

This blog breaks down how async and sync reviews work, where each performs best, and how to decide which approach fits your remote team.

TLDR

• Asynchronous code review lets reviewers comment when convenient without scheduling coordination. Research shows 58.8% time savings with async methods compared to synchronous approaches.

• Async works well for routine reviews, distributed time zones, and maintaining focus time. Synchronous code review works better for complex architectural discussions, onboarding new developers, and resolving disagreements. 

• Remote teams typically use async as the default with sync sessions for specific cases. AI-based code review tools handle routine checks asynchronously, freeing human reviewers for high-value sync discussions. 

• The combination of automated async review and selective sync sessions creates the fastest, most effective code review process for distributed teams.

How does async code review work?

Asynchronous code review doesn’t require real-time coordination. Developers open pull requests, and reviewers examine the code and leave comments when it fits into their schedule. No meetings required.

Once a pull request is opened, it enters the review queue. Reviewers leave inline comments, request changes, or approve the PR. The author is notified, addresses the feedback, and pushes updates. Reviewers then revisit the changes and continue the discussion asynchronously.

This loop continues until the pull request is approved and merged.

When async works best

Async code review excels in specific situations.

1. Distributed time zones: Teams spanning multiple timezones can't always find overlapping work hours. Async removes the need for coordination.

2. Routine reviews: Standard pull requests following established patterns don't need discussion. Reviewers check for common issues and approve.

3. Focus time: Research from UC Irvine professor Gloria Mark shows it takes an average of 23 minutes to fully refocus after an interruption. Async reviews let developers maintain focus without constant context switching.

4. Large teams: When multiple reviewers need to examine code, coordinating everyone for a sync session becomes impractical. Async lets each reviewer contribute when convenient.

How sync code review works

Synchronous code review happens in real time. Reviewers and authors meet over a video call or screen share to walk through the code together and discuss changes as they go.

The author schedules a review session and presents the changes, explaining the approach and reasoning. Reviewers ask questions, flag issues, and discuss alternatives during the session. Problems are addressed collaboratively instead of through back-and-forth comments.

The session ends with clear next steps, either the code is approved, or specific changes are agreed on before the pull request moves forward.

When sync works best

Synchronous review is valuable for specific scenarios.

1. Complex changes: Architectural decisions, major refactors, or changes touching many files benefit from real-time discussion. Async comments can't capture the nuance of design tradeoffs.

2. Disagreements: When reviewers and authors disagree on approach, async comments turn into lengthy threads. A 10-minute video call resolves what would take hours of back-and-forth comments.

3. Knowledge transfer: Teaching new patterns or onboarding junior developers works better synchronously. Real-time explanation with questions and answers accelerates learning.

4. High-stakes code: Security-critical changes or core infrastructure modifications deserve thorough discussion. Sync sessions ensure everyone understands implications.

Async vs Sync Code Review for Remote Teams

Async and sync code reviews solve different problems, and the tradeoffs become clear when you compare them side by side.

How AI code review fits into async and sync

AI-based code review tools handle routine checks asynchronously, changing what human reviewers need to focus on.

1. Automated async review

AI code review platforms examine every pull request automatically. They check for common issues like security vulnerabilities, code style violations, performance problems, missing tests, and documentation gaps.

This happens asynchronously without any human involvement. Developers get feedback within minutes of opening a PR. Issues get flagged before human reviewers even see the code.

2. Freeing humans for sync value

When AI handles routine checks, human reviewers focus on what requires human judgment. Architectural decisions, business logic validation, code readability for future maintainers, and design pattern appropriateness.

These higher-value reviews often benefit from synchronous discussion. Purpose-built code review platforms identify which PRs need human attention and which can auto-approve after AI review.

The hybrid code review approach

Modern remote teams use a three-tier system.

Tier 1 - Automated async: AI reviews every PR immediately. Simple changes passing all checks merge without human review.

Tier 2 - Human async: PRs flagged by AI or touching critical code get human async review. Reviewers examine and comment when convenient.

Tier 3 - Synchronous discussion: Complex changes, disagreements, or architectural decisions trigger sync sessions.

This helps the team move faster while still giving critical changes the attention they need.

Tools that support async and sync review

Different tools optimize for different review styles.

1. GitHub and GitLab

Pull request workflows in GitHub and merge request workflows in GitLab default to async. Reviewers comment when they visit. Threads track async discussions.

Both platforms support sync review through screen sharing and their interfaces, but the design favors async.

2. Specialized review tools

Some tools, like Gerrit or Phabricator, add structure to async review with formal approval workflows and dependency tracking between changes.

Others, like Tuple or CodeStream, integrate real-time collaboration directly into the code editor, making sync sessions easier.

3. AI review integration

AI coding agents provide instant async feedback. They analyze code in seconds, leaving comments that look like human reviewer feedback but arrive immediately.

This accelerates async review by handling the mechanical checks that would otherwise wait for human reviewers.

Making the async vs sync decision

Remote teams need guidelines for when to use each approach.

Default to async for

Standard feature work follows established patterns, bug fixes with clear solutions, documentation updates, test additions, dependency updates, and refactors that don't change architecture.

Switch to sync for

New architectural patterns, changes to core infrastructure, security-critical modifications, disagreements that would take multiple async rounds, onboarding explanations for new team members, and design discussions requiring whiteboarding.

Team agreements matter

What works for one team might not work for another. Teams should establish clear guidelines about when sync review is expected.

Some teams schedule weekly sync review sessions for any PRs needing discussion. Others keep everything async unless someone specifically requests sync time.

Maintaining clean architecture becomes easier when teams agree on review approaches for different types of changes.

Building effective async code review practices

Successful async review requires deliberate practices.

Clear expectations

Teams need a shared understanding of review timelines. Is a same-day response expected? Within 24 hours? Different urgency for different PR types?

Without clear expectations, developers don't know when to follow up on unreviewed PRs.

Thorough PR descriptions

Async reviewers can't ask the author questions in real-time. PR descriptions must answer common questions proactively.

What problem does this solve? What approach was chosen and why? What alternatives were considered? What testing was done? What areas need extra scrutiny?

Automated checks first

Run automated checks before requesting human review. Linting, tests, security scans, and AI code review should all be completed first.

This ensures human reviewers don't waste time finding issues that automation catches.

Finding the right code review balance for remote teams

Remote work is permanent for many teams. Code review practices continue evolving to fit distributed collaboration.

AI handles more routine review work, making async review faster. Automated code review tools catch common issues within seconds. Human reviewers focus on design, architecture, and business logic.

Sync review becomes more targeted. Instead of reviewing every line together, teams use sync time for design discussions and complex decisions.

The combination creates the best of both approaches. Fast async review for routine work, supplemented by high-value sync sessions for important decisions.

Ready to optimize your remote code review process? 

Book a demo with cubic to see how AI-based code review accelerates async workflows while freeing your team for high-value sync discussions.