Trunk-Based Development (TBD)

Trunk-Based Development (TBD) is a version control strategy where developers integrate small, frequent changes directly into a shared branch (typically 'main' or 'trunk').
It supports faster feedback, reduces merge conflicts, and enables continuous integration and delivery.

TBD underpins elite DevOps performance by promoting short feedback loops, simplicity in merging, and rapid flow.

Level 1 – Initial (Ad Hoc)

There is no defined branching strategy.
Teams often use long-lived feature branches that diverge significantly from the main codebase, leading to complex merges and integration failures.

  • Developers work in isolation for extended periods
  • Merges are infrequent, painful, and high-risk
  • Integration is delayed until the end of development cycles
  • Releases are delayed by "integration hell"

Level 2 – Managed (Emerging Practice)

Some teams use short-lived branches and merge changes more frequently.
However, trunk-based workflows are not standardised or consistently adopted.

  • Feature branches exist but may still live for days or weeks
  • Integration is done more frequently but not daily
  • There’s basic awareness of the value of frequent merges
  • Some teams experience fewer merge conflicts, but others still struggle

Level 3 – Defined (Standardised)

Trunk-Based Development is the default branching strategy.
Teams merge small changes to the trunk at least once per day, and integration is tightly coupled with CI.

  • Daily commits to trunk are expected and monitored
  • Teams use feature flags to separate release from deployment
  • Peer reviews are fast and embedded in daily flow
  • Branches are short-lived and limited to small, testable changes
  • Merges are fast, and the trunk is always in a releasable state

Level 4 – Quantitatively Managed (Measured & Controlled)

TBD effectiveness is measured, and data drives continuous improvements to developer workflow and deployment cadence.

  • Metrics include merge frequency, PR cycle time, and batch size
  • Teams track time from code commit to trunk merge
  • Tooling supports visibility into branch duration and divergence
  • Practices are reinforced through training, code reviews, and pipeline policies

Level 5 – Optimising (Continuous Improvement)

Trunk-Based Development is a cultural norm and technical foundation for rapid, safe delivery.
Teams continuously evolve branching strategies to maximise flow efficiency and feedback.

  • TBD is deeply integrated with CI/CD and testing strategies
  • Teams experiment with pairing/mobbing, review automation, and branching policies
  • Insights from trunk commits inform architectural improvements and testing strategies
  • Trunk-based flow enables decoupled deployments and safe experimentation