Open Banking API Standards: Driving Digital Asset and Fintech Integration

The financial services industry stands at a transformative crossroads where traditional banking infrastructure converges with blockchain-based digital assets.

This convergence, powered by open banking API standards, is reshaping how value flows across global financial ecosystems.

As we advance through 2025, the question is no longer whether traditional finance and digital assets will integrate, but how rapidly this integration will accelerate and which institutions will lead the charge.

Open banking APIs represent the architectural foundation enabling this transformation. By standardizing how financial data is accessed, shared, and utilized across institutions, these APIs are creating unprecedented opportunities for innovation, competition, and financial inclusion.

From tokenized assets and stablecoin payments to decentralized finance (DeFi) integration, standardized APIs are breaking down the barriers that have historically separated traditional banking from emerging digital asset ecosystems.

The evolution of open banking frameworks from the EU's Payment Services Directive 2 (PSD2) to emerging PSD3 regulations, the UK's pioneering Open Banking Implementation Entity standards, and the US Financial Data Exchange (FDX) has created a global infrastructure capable of supporting the next generation of financial services.

With open banking API call volumes projected to surge from 137 billion in 2025 to 720 billion globally by 2029, representing a 427% increase, the momentum behind standardized financial data sharing is undeniable.

What Are Open Banking API Standards?

Open banking API standards are the technical specifications, protocols, and governance frameworks that enable secure, standardized communication between financial institutions, third-party providers (TPPs), and customers.

These standards ensure that different financial systems can interoperate seamlessly, allowing customers to share their financial data with authorized parties and initiate transactions across multiple platforms.

Major API Standard Frameworks

Berlin Group NextGenPSD2

The Berlin Group, comprising participants from eurozone and surrounding countries, has developed the most widely adopted API framework in Europe.

The NextGenPSD2 standard provides comprehensive specifications for account information services (AIS) and payment initiation services (PIS), supporting the EU's PSD2 regulatory requirements.

As of 2025, the Berlin Group framework supports new European payment schemes and continues to evolve toward broader Open Finance applications.

UK Open Banking Standard

Developed by the Open Banking Implementation Entity (OBIE), the UK standard requires the nine largest UK banks (CMA9) to provide standardized APIs for account access and payment initiation.

The UK framework has achieved remarkable adoption, with 13.3 million active users as of March 2025, a 40% year-over-year increase.

The UK model emphasizes strong customer authentication (SCA) through OAuth 2.0 and OpenID Connect protocols.

Financial Data Exchange (FDX)

Operating primarily in North America, FDX has established the largest customer reach in the United States, with over 76 million consumer accounts using its API standard as of March 2024.

FDX provides a common technical specification covering over 600 different data elements that consumers may need when sharing their banking, tax, insurance, or investment data.

Unlike Europe's regulation-led approach, FDX represents a market-driven standardization effort that has gained significant traction.

2024-2025 Adoption Landscape

According to Cambridge Centre for Alternative Finance research analyzing 95 jurisdictions globally, 54 have adopted regulation-led open banking frameworks while 28 employ market-driven approaches.

The global open banking market grew from $30.89 billion in 2024 to $38.86 billion in 2025, demonstrating robust year-over-year expansion. Significantly, the market is projected to reach a compound annual growth rate (CAGR) of 19.2% between 2025 and 2034.

Consistent API structures promote several critical outcomes:

• Interoperability: Financial institutions using standardized APIs can integrate with multiple service providers without custom development for each connection
• Compliance: Standardized frameworks embed regulatory requirements including data protection, consent management, and security protocols
• Security: Common authentication standards like OAuth 2.0 and mutual TLS (mTLS) ensure consistent protection across the ecosystem
• Scalability: TPPs can build services once and deploy across multiple markets using compatible API standards

The shift from proprietary, screen-scraping methods to standardized APIs has fundamentally improved data security and customer control.

Where legacy systems required customers to share banking credentials with third parties, modern API standards enable granular permission management with the ability to revoke access at any time.

Digital Asset and Fintech Integration Challenges

Despite the promise of convergence between traditional finance and digital assets, significant barriers remain.

These challenges span technical, regulatory, and operational dimensions, each requiring thoughtful solutions before seamless integration can become reality.

Security and Infrastructure Incompatibility

Traditional banking systems operate on centralized, account-based infrastructure with batch processing and periodic settlement.

Digital asset systems function on decentralized, distributed ledgers with near-instantaneous settlement and 24/7 availability. Bridging these architectural paradigms requires sophisticated middleware capable of translating between fundamentally different data structures and transaction models.

The security models also differ substantially. Banks rely on perimeter security, authentication hierarchies, and reversible transactions.

Blockchain systems employ cryptographic security, immutable transactions, and wallet-based custody. Creating secure interfaces between these systems demands careful protocol design to prevent vulnerabilities at integration points.

KYC/AML Compliance Complexity

Know Your Customer (KYC) and Anti-Money Laundering (AML) requirements represent perhaps the most substantial challenge in digital asset integration.

Traditional financial institutions maintain established procedures for customer identification, transaction monitoring, and suspicious activity reporting. Digital asset platforms, particularly decentralized protocols, often lack comparable infrastructure.

According to 2025 research on scaling AML in fintech, companies must now navigate KYC/AML demands across both fiat and blockchain ecosystems, requiring the ability to trace transactions through both traditional correspondent banking networks and on-chain analytics.

The European Banking Authority's June 2025 "No Action Letter" attempted to clarify the interplay between Markets in Crypto-Assets (MiCA) regulation and PSD2/PSD3, highlighting the regulatory uncertainty that persists at the intersection of traditional finance and digital assets.

Financial institutions integrating digital assets face several specific compliance challenges:

• Cross-chain transaction monitoring: Tracking value flows across multiple blockchain networks with different transparency characteristics
• Privacy coin complications: Addressing transactions involving privacy-enhancing technologies that obscure transaction details
• DeFi protocol interactions: Understanding customer engagement with decentralized protocols that may lack traditional counterparty relationships
• Regulatory fragmentation: Navigating inconsistent regulatory approaches across jurisdictions, with some embracing digital assets while others maintain restrictive policies

Data Governance and Privacy

Digital assets introduce unique data governance considerations. Blockchain transactions are typically immutable and publicly visible (at least in pseudonymous form), creating potential conflicts with data protection regulations like GDPR that mandate data deletion rights.

Financial institutions must develop frameworks that satisfy both blockchain transparency requirements and data privacy obligations.

Additionally, the question of data ownership becomes more complex. In traditional open banking, customers control their transaction data and grant access to TPPs.

In digital asset ecosystems, transaction data exists on public ledgers without a single custodian, raising questions about how consent and data sharing frameworks should function.

Real-World Integration Examples

Several institutions have pioneered digital asset integration despite these challenges:

Revolut has successfully integrated cryptocurrency trading into its banking app, serving as a bridge between traditional finance and digital assets. By 2024, Revolut reported 72% year-over-year revenue growth to £3.1 billion, partly driven by its crypto offerings. The platform leverages open banking APIs to enable seamless fiat-to-crypto conversions while maintaining compliance across 38+ markets.

Stripe announced significant digital asset initiatives in 2024, including native stablecoin support through its payment platform and the acquisition of Bridge for $1.1 billion. In September 2025, Stripe launched "Open Issuance," enabling businesses to launch and manage their own stablecoins with just a few lines of code, demonstrating how payment infrastructure providers are embracing tokenization.

Coinbase has worked to integrate traditional banking rails with crypto asset custody through partnerships and API connections with banking institutions. The exchange reports serving over 100 million customers globally and has implemented comprehensive API frameworks that enable developers to build fintech applications connecting fiat and digital assets.

These examples demonstrate that while challenges exist, practical solutions are emerging through careful technical design, regulatory engagement, and phased implementation approaches.

How Open Banking APIs Enable Digital Asset Innovation

Standardized APIs are proving instrumental in bridging the gap between traditional banking systems and blockchain-based digital asset platforms.

This convergence is enabling innovative use cases that leverage the strengths of both ecosystems.

Tokenized Assets and API Integration

Tokenization representing real-world assets as digital tokens on a blockchain requires seamless integration with traditional financial infrastructure. Open banking APIs facilitate this by providing standardized interfaces for:

• Asset verification: Confirming ownership of underlying assets through bank account connections
• Payment initiation: Enabling investors to purchase tokenized securities using traditional bank accounts
• Settlement coordination: Synchronizing delivery of tokens with payment settlement through banking systems
• Regulatory reporting: Automating compliance reporting by connecting tokenization platforms with regulated financial institutions.

The BlackRock USD Institutional Digital Liquidity Fund ($2.9 billion), Franklin OnChain U.S. Government Money Fund ($0.8 billion), and Ondo Short-Term US Treasuries Fund ($0.7 billion) exemplify yield-bearing tokenized assets that integrate with traditional finance through API connections.

These products demonstrate how standardized interfaces enable institutional investors to access blockchain-based investments while maintaining banking relationships.

Stablecoin Integration and Open Banking

Stablecoins cryptocurrencies pegged to fiat currencies represent a critical use case for open banking API integration. McKinsey researchprojects stablecoin circulation could grow from $250 billion in 2025 to over $2 trillion by 2028, with daily transaction volumes potentially reaching $250 billion within three years.

Open banking APIs enable stablecoin functionality in several ways:

• On-ramp and off-ramp services: Payment initiation APIs allow users to purchase stablecoins directly from bank accounts and redemption APIs enable conversion back to fiat currency without multiple intermediary steps.
• Treasury management: Corporate treasury systems integrate stablecoins through APIs that enable real-time liquidity positioning, allowing companies to hold dollar-denominated value on-chain while maintaining traditional banking relationships.
• Cross-border payments: Stablecoins combined with open banking APIs create efficient cross-border payment corridors. Funds move from sender's bank account to stablecoin, transfer across borders near-instantaneously on blockchain rails, then convert to local currency in recipient's bank account, all orchestrated through API calls.

DeFi-to-Bank API Models

Decentralized finance (DeFi) protocols offer financial services without traditional intermediaries, but integration with regulated banking systems remains essential for mainstream adoption. Open banking APIs are enabling new hybrid models:

DeFi lending with bank verification: Lending protocols can verify borrower income and assets through account information APIs while maintaining decentralized loan execution on-chain.

Automated yield optimization: Platforms aggregate yields across DeFi protocols and traditional savings products, using APIs to move funds between ecosystems based on risk-adjusted returns.

Programmable payment rails: Smart contracts trigger bank payments through payment initiation APIs based on on-chain conditions, enabling automated treasury management and conditional payments.

Regulatory Framework Support: ISO 20022, PSD3, and MiCA

Contemporary regulatory frameworks increasingly recognize and accommodate digital asset integration:

ISO 20022

The ISO 20022 messaging standard for financial communications includes data fields capable of supporting digital asset transactions.

SWIFT's migration to ISO 20022, completed in October 2025, provides enhanced data richness that can accommodate cryptographic identifiers and blockchain transaction references. This creates a pathway for traditional payment messages to reference on-chain settlements.

PSD3 and PSR

The proposed Payment Services Directive 3 (PSD3) and Payment Services Regulation (PSR), expected to be finalized in 2025-2026, introduce stronger fraud liability frameworks, enhanced open banking provisions, and provisions for emerging payment methods.

While not explicitly crypto-focused, PSD3's technology-neutral approach accommodates digital asset payment methods that meet defined security standards.

Markets in Crypto-Assets (MiCA)

The EU's MiCA regulation, which became fully applicable in 2024-2025, creates a comprehensive framework for crypto-assets including stablecoins (termed "e-money tokens" and "asset-referenced tokens").

MiCA's licensing requirements for crypto asset service providers (CASPs) and reserve requirements for stablecoin issuers provide the regulatory clarity needed for bank-CASP API integrations. The EBA's June 2025 "No Action Letter" specifically addressed how MiCA interacts with PSD2 payment initiation services, reducing regulatory uncertainty at the convergence point.

Technical Architecture: OAuth 2.0, RESTful APIs, and Secure Data Sharing

Modern open banking implementations leverage proven security and architectural patterns that readily extend to digital asset use cases:

OAuth 2.0 Authorization Framework

OAuth 2.0 provides token-based authorization without sharing credentials, ideal for granting digital asset platforms limited access to bank accounts.

The protocol supports granular permission scopes (e.g., "read account balance" vs. "initiate payment"), time-limited access, and user-controlled revocation, all essential for secure digital asset integration.

The January 2025 RFC 9700 ("Best Current Practice for OAuth 2.0 Security") reflects lessons learned from open banking implementations and provides updated security guidance applicable to fintech and digital asset scenarios.

RESTful API Architecture

REST (Representational State Transfer) APIs use standard HTTP methods, making them accessible to developers regardless of platform.

The stateless nature of REST aligns well with blockchain transaction models, and the use of JSON data formats provides flexibility for representing both traditional financial and blockchain-specific data.

The Berlin Group, UK OBIE, and FDX standards all employ RESTful architecture, creating a consistent developer experience across jurisdictions. This standardization reduces integration costs for digital asset platforms operating internationally.

Mutual TLS and API Security

Open banking frameworks mandate mutual Transport Layer Security (mTLS), where both client and server authenticate using certificates.

This prevents unauthorized API access and man-in-the-middle attacks. Combined with OAuth 2.0, mTLS creates a defense-in-depth security model appropriate for high-value financial transactions involving both fiat and digital assets.

Industry Data and Expert Insights

Data from 2024-2025 demonstrates tangible progress:

Juniper Research projects open banking API calls will increase from 137 billion (2025) to 720 billion (2029), driven partly by AI-powered personalization and expanding use cases including digital asset integration.

Cambridge Centre for Alternative Finance found that regulation-led open banking frameworks cover broader data types (average score 2.69/6) compared to market-driven approaches (1.75/6), suggesting regulatory mandates accelerate comprehensive implementation.

World Economic Forum reports that Middle East & Africa represent high-growth open banking markets, with regulatory frameworks in Saudi Arabia and the Open Finance African Group Framework creating opportunities for leapfrog adoption of combined traditional and digital asset services.

The convergence of standardized APIs, maturing regulatory frameworks, and proven security protocols is creating the infrastructure foundation for seamless traditional finance-digital asset integration.

As these technical standards continue to evolve, the gap between ecosystems will continue to narrow, enabling the programmable, interconnected financial services of tomorrow.

Future Outlook

The trajectory of open banking API standards points toward a more interconnected global financial system where traditional banking, digital assets, and emerging technologies converge into unified "Open Finance" ecosystems.

Evolution Toward Open Finance

Open Finance extends beyond payment accounts to encompass loans, savings, investments, pensions, insurance, and increasingly, digital assets.

According to Cambridge research, while 60 jurisdictions have implemented open banking legislation, only 16 have enacted Open Finance regulations as of 2025. However, this gap is rapidly closing as jurisdictions recognize the benefits of comprehensive financial data portability.

The UK Financial Conduct Authority's March 2025 "Open Finance Sprint" brought together 110 stakeholders to develop practical use cases spanning financial wellbeing, growth, resilience, and digital verification. The FCA's 5-year strategy (2025-2030) places the "smart data revolution" at its core, emphasizing commercial sustainability of open banking and its evolution into open finance.

Significantly, Open Finance frameworks are being designed from inception to accommodate digital assets. India's Account Aggregator framework, for instance, already enables consent-based data sharing across traditional financial products and is positioned to incorporate digital asset holdings as regulatory clarity emerges.

Global Collaboration and Interoperability Initiatives

Cross-border interoperability remains a critical challenge and opportunity. Several initiatives are addressing this:

Regional Alignment

Europe's PSD2/PSD3 framework has created a standardized approach across 27+ member states, demonstrating how regional cooperation can achieve scale.

Similarly, the Open Finance African Group Framework, launched in 2024, is creating harmonized standards across key African markets.

International Standards Bodies

Organizations like the Financial Stability Board (FSB), Bank for International Settlements (BIS), and ISO are developing principles and standards for cross-border data sharing and payment interoperability.

The BIS Innovation Hub's Project mBridge, involving central banks from China, Hong Kong, Thailand, and UAE, explores tokenized central bank money for cross-border settlement, a potential model for international digital asset transactions.

API Standard Convergence

While regional API standards differ, efforts are underway to create translation layers and shared principles.

The World Economic Forum's 2025 report on "The Future of Global Fintech" identifies regional interoperability and open banking/open finance as critical drivers for 2025-2030 development, alongside AI integration.

Digital Asset Custody and Tokenization Standards

The future infrastructure must address digital asset custody within open finance frameworks. Traditional open banking focuses on account access; digital asset custody requires secure key management and transaction signing. Emerging standards are addressing this:

Qualified digital asset custodians are being recognized in regulatory frameworks, with capital requirements and security standards comparable to traditional custodian banks.

API standards for custody services are under development, enabling standardized interfaces for depositing, withdrawing, and transacting with custodied digital assets.

Cross-chain interoperability protocols like Polkadot's XCM and Cosmos IBC are creating foundations for value transfer across blockchain networks, analogous to how open banking APIs enable transfers across banks.

State Street's July 2025 research on digital asset custody emphasizes that "future growth of digital assets depends on the emergence of bank-grade custody solutions that can integrate with existing financial infrastructure."

Forecasts and Trend Projections

Market Growth

The global open banking market is projected to grow from $38.86 billion (2025) to over $100 billion by 2030, with digital asset integration representing an increasing share.

Sahamati's Global Open Finance Adoption Report projects open finance could reach 1 billion users globally by 2030.

Stablecoin Integration

McKinsey forecasts stablecoin circulation reaching $2 trillion by 2028, with daily transaction volumes potentially exceeding $250 billion surpassing major card networks.

This growth depends partly on seamless integration with traditional banking through standardized APIs.

Tokenization of Traditional Assets

Real-world asset tokenization is projected to unlock trillions in value by making traditionally illiquid assets like real estate, private equity, and infrastructure tradeable 24/7 through blockchain rails.

Boston Consulting Group estimates tokenized assets could reach $16 trillion by 2030, requiring extensive traditional finance-blockchain API integration.

AI-Enhanced Open Finance

Juniper Research notes that API quality requirements are increasing, with generative AI (GenAI) enabling personalization at scale.

AI will analyze data flowing through open banking APIs to provide predictive financial insights, automated investment recommendations, and dynamic risk assessment, capabilities equally applicable to digital asset portfolios.

Programmable and Connected Finance

The ultimate vision is "programmable finance" where money itself becomes programmable through smart contracts and API integration. This enables:

Conditional payments that execute automatically when specified conditions are met
Embedded finance where financial services integrate seamlessly into non-financial platforms
Autonomous treasury management where AI agents optimize liquidity across traditional and digital asset holdings based on real-time yield opportunities.

Fractional ownership of high-value assets made accessible through tokenization and banking integration.

As one financial innovation leader recently observed, "The future of finance is not about choosing between traditional banking and digital assets - it's about creating interoperable infrastructure where value flows freely between systems based on efficiency, security, and user needs."

Conclusion

Open banking API standards have emerged as the critical infrastructure enabling convergence between traditional financial services and digital asset ecosystems.

Through standardized frameworks like Berlin Group, UK Open Banking, and FDX, the industry has established interoperable foundations that extend beyond simple data sharing to encompass payment initiation, account aggregation, and increasingly, digital asset integration.

The journey from PSD2 to emerging PSD3 and MiCA frameworks demonstrates regulatory evolution keeping pace with technological innovation.

With 95 jurisdictions now implementing some form of open banking or open finance, and API call volumes projected to grow over 400% to reach 720 billion by 2029, the momentum behind standardized, API-driven financial services is undeniable.

Yet challenges remain. KYC/AML compliance across traditional and digital asset domains, security at blockchain-banking integration points, and cross-border regulatory harmonization all require continued attention.

However, real-world implementations by institutions like Revolut, Stripe, and Coinbase demonstrate that these challenges are surmountable through thoughtful technical architecture and regulatory engagement.