Rewriting All of Spotify's Code Base, All the Time

We don't need LLMs to write new code. We need them to clean up the mess we already made.

In mature organizations, we have to maintain and migrate the existing codebase. Engineers are constantly balancing new feature development with endless software upkeep.

But what if you could rewrite your codebase, every single day, across thousands of repositories? What if your engineers didn't have to maintain their code?

At Spotify, we are seeing early success using LLMs to perform predictable, repeatable and effortless code migrations.

In this talk, we’ll share how we created an Agentic Migrator that has gotten over 3000 PRs merged across several engineering disciplines. We will tell you how we reason about solving the complexity of LLMs maintaining code at scale. From managing build feedback loops across thousands of repos, to evaluating prompt effectiveness and mastering the sheer complexity of our diverse codebase.