API data gathering and structuring for machine learning and human use : Optimizing API data for both financial machine learning and being easy to read and use by the end user

Sammanfattning: This thesis looks into how to implement an abstraction layer between transaction data gathered from Revised Payment Services Directive (PSD2) compliant banks via an Application Programming Interface (API) and a data base, with a human user interface for reading and structuring the data. API for data sources tend to not have a standardized structure and this creates a problem for machine learning. The result is that the machine learning component either has to be built around the data collected from the API or the data to be transformed and reformatted to fit the structure of the machine learning component's database. An application will use the abstraction layer to fetch data and to allow the user to set up how the data should be reformatted before being sent to the machine learning component's database. The application has to display the data in an easy to read format and the application needs to be usable by a human user. The main questions are (i) how this abstraction should be implemented, (ii) how much of it can be automated, and (iii) what is the optimal design for the components. PSD2 open banking systems in Sweden are using Representational State Transfer (REST) API and provide data in the JavaScript Object Notation (JSON) format, and can be considered the de facto standard. The abstractions can be divided into three areas: Authorization, Account and transaction access, and Transaction data. Out of these areas only the transaction data could be abstracted fully. The account and transaction access process could be partly abstracted while the authorization process can only be broken down into steps as there is no possibility of abstracting the parameters used by the different banks. The project aimed to produce a fully functioning application for gathering data via PSD2 open banking where the user can configure the application through a simple system that does not require the user to have a lot of knowledge about coding. While the process of fetching transaction data from PSD2 API is simplified, the goal of being useful to a person without knowledge of coding is currently impossible unless PSD2 open banking is standardized or more advanced tools are used.