By Arjun Mehta

Trunk-Based Development: Why Top Teams Ship Faster Without Long-Lived Branches

Long-lived branches feel safe. They let developers work in isolation, building complete features before integration. They provide a buffer before code hits production.

They also make teams slower.

Trunk-based development—where the main branch is always deployable and developers work on short-lived branches or directly on trunk—is how elite engineering teams ship faster. Companies like Google, Facebook, and Netflix have been using this pattern for years. In 2026, it's not an option for high-performing teams. It's the default.

This guide explains why, how to migrate to it, and how to manage the real challenges it creates.

The Cost of Long-Lived Branches

When developers work on long-lived branches, they're solving two problems simultaneously:

1. Building their feature in isolation
2. Staying synchronized with changes from other teams

This creates a cascading problem. The longer your branch lives, the more changes happen on main. When you finally merge, you're resolving increasingly complex conflicts. Code review becomes difficult because the change is massive. Testing takes longer. Deployment risk increases.

Metrics that show the problem:

• Long-lived branches correlate with longer code review times
• Large pull requests have exponentially higher defect rates
• Merge conflicts increase exponentially with branch duration
• Mean time to deploy (MTTR) increases with branch complexity

The DORA Metrics (used by Google to measure deployment performance) show that elite teams have:

• 96% deployment frequency (daily deployments)
• Small pull requests (typically <100 lines of code)
• Fast code review cycles (< 1 hour)

None of this is possible with long-lived branches.

What Is Trunk-Based Development?

Trunk-based development is simple:

1. The main branch (trunk) is always deployable
2. Developers work on short-lived feature branches (typically 1-3 days)
3. Code is integrated frequently (multiple times per day)
4. Every commit can go to production (with feature flags if needed)

The key difference: frequency over isolation.

Instead of building complete features in isolation and merging infrequently, trunk-based teams integrate code constantly. Each integration is small, easy to review, and low-risk.

Why Trunk-Based Development Works

1. Small Pull Requests Are Easier to Review

Research shows that code review quality drops dramatically when reviewing large PRs:

• < 100 lines: Reviewers can understand the full context
• 100-400 lines: Review quality starts degrading

• 400 lines: Reviewers miss many issues

Small, frequent PRs mean:

• Faster review cycles
• Higher code quality (better review)
• Less context switching
• Faster feedback loops

2. Merge Conflicts Become Trivial

With frequent integration, conflicts are rare and small. You're merging every day, so you're never far out of sync with trunk.

Compare:

• Long-lived branches: Merging after 3 weeks, 500+ conflict points
• Trunk-based: Merging after 1 day, 1-2 conflict points

3. Deployment Risk Drops

When every commit is ready for production, you can deploy frequently. Small, frequent deployments are much lower risk than large, infrequent ones:

• Easier to identify the commit that caused issues
• Faster rollback
• More confidence in the release
• Easier to validate in production

4. Knowledge Spreads Faster

With constant integration, everyone sees what everyone else is working on. Code patterns spread naturally. Architectural decisions are made with full context.

With long-lived branches, developers work in silos. Duplicated code, divergent patterns, and architectural conflicts go unnoticed until merge time.

Feature Flags: The Missing Piece

One concern about trunk-based development: "What if we're not ready to release a feature?"

The answer is feature flags.

Feature flags (or feature toggles) let you merge incomplete code to trunk and deploy it to production while hiding it behind a flag. The code is live, but it's invisible to users until you flip the flag.

This is how Netflix deploys thousands of times per day while maintaining stability.

Good feature flags are:

• Temporary (removed after feature launches)
• Simple (easy to evaluate)
• Safe (default to off)
• Scoped (affect only what they need to)

if feature_flag.is_enabled('new_payment_flow'):
    return PaymentFlowV2()
else:
    return PaymentFlowV1()

Continuous Integration: Non-Negotiable

Trunk-based development requires rock-solid continuous integration:

Your CI/CD Pipeline Must Be Fast

If your test suite takes 45 minutes to run, developers will batch changes to avoid waiting. Tests should run in < 10 minutes. If they don't, fix your tests first.

Your Pipeline Must Be Reliable

Flaky tests kill trunk-based development. When tests fail intermittently, developers start ignoring failures. Invest in making your tests reliable.

Your Pipeline Must Prevent Broken Code from Reaching Main

Every commit to main should pass:

• Automated tests
• Linting and formatting
• Security scanning
• Integration tests

If broken code reaches main, your trunk is no longer always deployable.

Migrating to Trunk-Based Development

Phase 1: Assess Your Current State

1. Measure your baseline:

   • Average branch lifetime
   • Average PR size
   • Code review time
   • Deployment frequency
   • Incident rate

2. Identify blockers:

   • Is your test suite too slow?
   • Are your tests unreliable?
   • Do you lack feature flag infrastructure?
   • Is code review a bottleneck?

Phase 2: Build the Infrastructure

1. Feature flags: Implement infrastructure to toggle features safely
2. Fast tests: Parallelize tests, remove slow tests, improve test quality
3. Reliable CI/CD: Fix flaky tests, ensure every commit is validated
4. Monitoring: Instrument your code to detect issues in production

Phase 3: Change the Culture

1. Start with one team: Not the entire company
2. Make integration the default: Encourage PRs every day, not every week
3. Celebrate small commits: Make frequent integration the norm
4. Monitor metrics: Track deployment frequency, PR size, review time

Phase 4: Scale Across Teams

Once one team proves it works, expand the practice.

Challenges and How to Handle Them

Challenge 1: "Our code isn't ready for production"

Solution: Use feature flags. Deploy to main and production, but keep the feature hidden until it's ready.

Challenge 2: "We'll break the main branch constantly"

Solution: Strong CI/CD gates. If code breaks tests, it doesn't reach main. Invest in testing first.

Challenge 3: "Code review will be a bottleneck"

Solution: Small PRs. When PRs are < 100 lines, review is fast. Invest in asynchronous code review tools.

Challenge 4: "We need to maintain multiple versions"

Solution: Branch for maintenance releases only. Main stays on the latest version. Backport critical fixes.

Trunk-Based Development at Scale

Google uses trunk-based development across 10,000+ engineers. They've built it at massive scale:

• Single main branch for nearly all code
• Feature flags for all major features
• Automated testing catches issues before human review
• Quick code review (usually < 24 hours)
• Rapid integration (thousands of commits per day)

If it works for Google's scale, the limitation isn't the approach. It's the infrastructure and discipline.

Metrics That Matter

When migrating to trunk-based development, track these metrics:

1. Deployment frequency: How often do you deploy? Aim for multiple times per day
2. Lead time for changes: How long from commit to production? Aim for < 1 hour
3. Mean time to recovery: How long to fix a production incident? Aim for < 1 hour
4. Change failure rate: What % of deployments cause issues? Aim for < 5%

These are the DORA metrics. They're proven indicators of team performance.

Getting Started

1. Pick a team to pilot trunk-based development
2. Measure current state (branch lifetime, PR size, review time)
3. Build feature flag infrastructure
4. Improve your CI/CD pipeline (speed and reliability)
5. Set cultural norms (small commits, frequent integration)
6. Monitor metrics and iterate

Trunk-based development isn't a silver bullet. But combined with strong testing, feature flags, and monitoring, it's how top-performing teams achieve high deployment frequency and low incident rates.

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Frequently Asked Questions

Q: Won't trunk-based development make our main branch unstable? A: Only if your CI/CD is weak. With strong automated testing and gating, every commit is validated before it reaches main. The branch is more stable, not less.

Q: How do we handle code review feedback on production code? A: Use feature flags. Code is deployed but hidden. Once feedback is addressed and the feature is validated, flip the flag to enable it.

Q: What about large refactorings? A: Break them into small commits that keep the codebase working. Each commit compiles, tests pass, and the system is functional. This is harder but very doable.