Gusto is a cloud-based Human Resource Information System (HRIS) designed to streamline and automate HR operations, offering tools for payroll, benefits, and HR management. It allows businesses to access employee data and optimize workflows through its API, which can be integrated using various programming languages like Python. The process involves obtaining an access token via OAuth 2.0, which is then used to make API calls to retrieve employee data. The detailed guide outlines steps to fetch employees and handle data intricacies such as pagination and custom fields. Additionally, it highlights that while Gusto is a robust HRIS solution, businesses can leverage platforms like Merge’s Unified API to integrate multiple HRIS solutions, thereby managing customer integrations more efficiently across various systems.