At Clerk, the use of End To End (E2E) testing has become essential for creating reliable authentication flows across different browsers, addressing the growing need for effective validation in agile development cycles. Initially a domain of Quality Assurance Engineering, E2E testing has gained popularity among software engineers due to the rise of tools like Cypress and Playwright, the latter of which Clerk selected for its flexibility and robust community support. Playwright's ability to seamlessly execute workflows across multiple browsers, combined with its stellar documentation, made it the platform of choice for Clerk’s E2E suite, which is designed as a separate Node.js application written in TypeScript. The suite incorporates components like Jest for test running and Faker.js for API fixtures, promoting ease of use and quick onboarding for new team members. Integration with GitHub Actions ensures that all tests run successfully before any production merges, safeguarding against accidental regressions. Clerk’s decision to open-source a template for E2E testing with Playwright underscores their commitment to sharing knowledge and advancing the field.