Standardisation of APIs and Security Protocols in the Integration of Banking Payment Solutions with Retail Partner Infrastructure

The article examines the standardization of APIs and security protocols in the integration of banking payment solutions with retail partner infrastructure. The aim of the study is to systematize architectural, procedural, and security approaches that govern the boundary between banking payment platforms and retailer systems. The relevance of the topic stems from the growth of embedded finance, co-branded card programmes, and partner-facing banking platforms, where integration failures may affect revenue, trust, auditability, and regulatory exposure. The novelty of the article lies in the proposed core-and-periphery model, which separates the standardized banking core from the controlled customization zone of retail partners. The main findings show that mature integration architectures require OpenAPI-based contracts, TLS 1.3, mTLS, OAuth 2.x, OpenID Connect, FAPI profiles, JWS, JWE, ISO 20022, PCI DSS, ISO/IEC 27001, and NIST-aligned API security practices. The study concludes that scalable partner onboarding depends on reusable artifacts, certification gates, unified observability, SLOs, incident runbooks, and coordinated release governance. The article will be useful for researchers, banking architects, API security specialists, payment platform teams, and retail partners involved in embedded finance integrations.