Modern web development often involves using JavaScript or TypeScript for both frontend and backend applications, commonly utilizing a React or Vue frontend with a NodeJS backend. Challenges arise in ensuring seamless integration between these components, particularly when dealing with complex APIs. A case study reveals how a simple typo in API field names can disrupt a system, highlighting the importance of type safety, which can be achieved using TypeScript to define API request and response types. Initially, the solution involved copy-pasting type definitions between frontend and backend, but this approach is prone to human errors. A proposed improvement involves publishing API types as a private NPM package, ensuring consistent updates across codebases. However, this approach still allows for discrepancies between frontend and backend versions. The text advocates for a monorepo strategy, where both frontend and backend reside in a single repository, providing a single source of truth and preventing API changes that could break integrations. While monorepos simplify code sharing and integration, they don't eliminate all risks, such as production incidents caused by asynchronous deployments. The text advises careful staging of changes and suggests implementing robust monitoring solutions to quickly address any issues that arise. Overall, the monorepo approach promotes efficiency and coordination across development teams by maintaining consistent and up-to-date code versions.