Central Bank Digital Currencies: A Survey

TL;DR

This survey reviews recent developments in CBDC system design, analyzing 135 papers to identify architectural trends, challenges, and future research directions in central bank digital currencies.

Contribution

It provides a comprehensive taxonomy and ecosystem framework for CBDCs, expanding on design elements and comparing 26 existing systems across key dimensions.

Findings

Most CBDCs use a two-tier architecture with DLT and token-based access.

No dominant application domain has emerged for CBDCs.

Growing research focus on cross-border payments using CBDCs.

Abstract

With the advancement of digital payment technologies, central banks worldwide have increasingly begun to explore the implementation of Central Bank Digital Currencies (CBDCs). This paper presents a comprehensive review of the latest developments in CBDC system design and implementation. By analyzing 135 research papers published between 2018 and 2025, the study provides an in-depth examination of CBDC design taxonomy and ecosystem frameworks. Grounded in the CBDC Design Pyramid, the paper refines and expands key architectural elements by thoroughly investigating innovations in ledger technologies, the selection of consensus mechanisms, and challenges associated with offline payments and digital wallet integration. Furthermore, it conceptualizes a CBDC ecosystem. A detailed comparative analysis of 26 existing CBDC systems is conducted across four dimensions: system architecture, ledger technology, access model, and application domain. The findings reveal that the most common configuration consists of a two-tier architecture, distributed ledger technology (DLT), and a token-based access model. However, no dominant trend has emerged regarding application domains. Notably, recent research shows a growing focus on leveraging CBDCs for cross-border payments to resolve inefficiencies and structural delays in current systems. Finally, the paper offers several forward-looking recommendations for future research.