Code Health Score: How Slack Tracks and Manages Code Tech Debt at Scale

All codebases have technical debt. Sometimes developers plan to clean it up later. Other times they act on the urge to go on a refactoring binge. Addressing technical debt can be rewarding and useful. But how can we make sure that it is not simply left to the whim of a good samaritan? And can such work be consistently seen and encouraged by engineering leadership?

Following the trope of “you can’t improve what you don’t measure,” Slack employs a code health score: an empirical measure that provides visibility into cumulative and team-based technical debt to address these questions. But measurement alone isn’t enough. Quality is important to integrate these measurements into the day-to-day engineering culture of the team.

This talk will provide the formula for building a code health score for any codebase, touch on the nuances of its implementation on Android/iOS, and share what lessons learned about integrating this tool into our engineering process.