The SaaS Startup Kit is an open-source project offering a collection of Go (Golang) libraries and boilerplate code to facilitate the development of scalable software-as-a-service applications. It includes a responsive web app with user authentication including sign-up, login, and create, read update and delete (CRUD). The kit includes an RESTful API, JSON Web Token authentication (JWT), and Swagger-generated documentation. It integrates Bootstrap for user interface design. This allows the creation of responsive and mobile-first projects. The deployment is streamlined by using serverless infrastructure in Amazon Web Services (AWS) with continuous integration and delivery pipelines configured through GitLab CI/CD. The SaaS Startup Kit reduces repetitive tasks by offering pre-built components, integrations and allowing developers to concentrate on unique business logic.