In this hands-on session, we crack open the IDE and transform a SaaS web app comprised of several monolithic single-tenant environments into an efficient, scalable, and secure multi-tenant SaaS platform using ReactJS and NodeJS serverless microservices. We use Amazon API Gateway and Amazon Cognito to simplify the operation and security of the service's API and identity functionality. We enforce tenant isolation and data partitioning with OIDC's JWT tokens. We leverage AWS SAM and AWS Amplify to simplify authoring, testing, debugging, and deploying serverless microservices, keeping operational burden to a minimum, maximizing developer productivity, and maintaining a great developer experience.