A look at Vercel's philosophy and techniques in AI-native development. AI changes how we build software. In combination with developers, it creates a positive feedback loop where we can achieve better results faster. However, traditional testing methods don't work well with AI's unpredictable nature. As we've been building AI products at Vercel, including v0 , we've needed a new approach: eval-driven development. This article explores the ins and outs of evals and their positive impact on AI-native development. Link to heading Evals: The new testing paradigm Evaluations (evals) are like end-to-end tests for AI and other probabilistic systems. They assess output quality against defined criteria using automated checks, human judgment, and AI-assisted grading. This approach recognizes inherent variability and measures overall performance—not individual code paths. Evals complement your existing test suite.…