Refactor Legacy Code Safely
Modernize your codebase without breaking production
Record live traffic, refactor with confidence, verify identical behavior. Turn months of manual test writing into days of safe modernization.
Refactor legacy code faster with peace of mind
Before
Traditional Approach
• Write tests manually: 3-6 months
• Put off refactoring until code freezes
• Coverage based on developers' gut
• Miss edge cases that happen in prod
• Hope nothing breaks
After
With Tusk Drift
• Record live traffic: 1 week
• Refactor whenever convenient
• Coverage from actual user behavior
• Capture real edge cases automatically
• Know nothing broke
Record real-world traffic before refactoring
Run Tusk Drift in staging or production at 1-10% sampling rate for a week to capture actual API behavior: HTTP requests, database queries, cache hits, and more
Code fearlessly with a safety net in place
Migrate from Express to Fastify, break up monoliths, and re-organize code with the security that your changes are checked for backwards compatibility
Verify that nothing breaks in your PR
Replay recorded traces against refactored code to ensure API behavior remains the same –– all tests green means you're good to merge
Stop being paralyzed by legacy code
Helpful resources on AI automated testing
Does Real API Traffic Make AI-Generated Tests Better? An A/B Evaluation of Tusk Drift
March 9, 2026
Scaling Parallel Agents with the Context-Verification-Harness Framework
March 8, 2026
What if Your Production Traffic Was Your Test Suite?
February 11, 2026
How Promptfoo Scaled Test Coverage Without Slowing Development
February 2, 2026