Cloud computing has gained wide popularity during last decade. More and more organizations and enterprises are moving their infrastructure in serverless platforms in order to enjoy the benefits and the flexibility that the cloud technology provides. Serverless platforms offer the possibility to deploy and execute services as functions f(x) and compose serverless workflows. Certain types of services, e.g., analytical services, require access to data in order to operate and provide results. Accessing external data resources in serverless environments can often become a problem due to several restrictions because of platform policies that might exist. Alongside this fact, specific efficiency considerations may arise regarding the long running tasks running on the cloud. Extracting data from different data sources is a challenging task in itself. There are literary countless external APIs, database technologies and file formats, that in order to be consumed different tools, libraries, or protocols need to be utilized. A unified gateway component, operating as a single point of entry for the cloud platform may prove to be the solution to these above-mentioned problems. The main goal of this component is to combine and orchestrate several microservices, each one responsible to collect data from a specific data source and additionally provide data-cleansing and data-transformation mechanisms in order to produce datasets that meet the standards of the gateway’s users . The collected data would be accessible via REST endpoints of a single API. The “Cloud Gateway”, as will be mentioned in the rest of this thesis, was designed, and implemented considering the problems and challenges of a production environment like load balancing, scalability, high availability, authentication, and authorization strategies etc. On top of this, state-of-the-art methodologies and tools will be utilized to achieve the goals without compromising performance. To avoid misinterpretation, the designation “Cloud Gateway” does not refer to a gateway that combines PaaS infrastructure from different cloud providers, but to a gateway that is acting as intermediate between any cloud platform and its external and heterogeneous data sources from which data should be fetched.