Revised European directive PSD2 about electronic payments contains regulations about new services which will be managed by the third-party providers in the name of the payment service users. Banks are obligated to make their payment services and data visible to licensed third-party companies. This thesis studies the PSD2 regulation and all of its directives. Within that, innovations and security specifications are studied in detail. Some of the existing API specifications are described, such as: PolishAPI, Berlin Group NextGenPSD2, Open Banking UK and STET PSD2 API. The adaptation of the croatian banks to the PSD2 will be analyzed. With exposing its payment services and data to third-parties, the banks have become a potential target to various hacking attacks. The solution which presents itself is developing a proxy that will supervise the access to the payment services exposed through PSD2. The main goal of this thesis is to design and develop that access control proxy. The proxy will have an ability to intercept, analyze and change the network traffic between participants. In that way, it protects the bank from possible hacking attacks. The agent is based on the microservice architecture. The communication between the independent components is achieved with messages queues and distributed message queue system RabbitMQ. Running of the proxy is possible from the cloud as an independent component or it can be integrated in the IT system of the bank. After analyzing the technologies used for the implementation of the system components, JavaScript runtime environment Node.js with its framework Express.js was chosen. Special attention was dedicated to the automated generation of the access programs based on the publicly available documentation of the PSD2. In the end, the proxy was tested using the Erste and RBA bank sandbox.