1Password used AI agents to break apart its monolithic codebase — and found the approach faster and cheaper than human refactoring

1Password deployed AI agents (self-directed AI software that can plan and execute multi-step tasks) to refactor its monolith—a single, tightly-integrated codebase that had become difficult to modify. The company documented what worked, what failed, and the business case in a public blog post, providing concrete lessons for other engineering teams facing similar architecture problems.

Instead of hiring contractors or dedicating senior engineers for months, AI agents could propose code changes, test them, fix errors automatically, and iterate—collapsing work that typically takes weeks into days. The key difference: agents didn't just suggest code; they debugged and refined their own output without human intervention between cycles.

For software teams drowning in technical debt, this demonstrates a concrete path to modernizing legacy systems without hiring freezes or massive budget requests. Engineering leaders now have proof that AI can handle architectural refactoring—traditionally considered a task requiring deep domain expertise—which means smaller teams can tackle infrastructure upgrades that were previously out of reach.