How to Implement Open Banking as a Data Provider: A Technical Guide

Implementing open banking as a data provider means exposing your institution's customer data through standardised APIs — securely, compliantly, and reliably. Whether your deadline is driven by regulation (CDR in Australia, Section 1033 in the US, PSD2/PSD3 in Europe) or by market pressure (fintechs and customers demanding API access), the implementation path follows a consistent pattern.

This guide walks through the key phases of going live as an open banking data provider.

Phase 1: Scoping and Assessment

Before building anything, you need to understand what's required.

Regulatory Requirements

Identify which open banking standard applies to your institution and what specific obligations you have:

Which data types must you share? (Product data, account data, transaction data, customer identity)
What timelines are you working to? (Regulatory deadlines, or competitive timing)
What security standards are mandated? (FAPI profiles, mTLS, specific authentication requirements)
What consent management requirements apply? (Consent duration, consumer dashboard, revocation)
Which third parties are authorised to request data? (Accredited data recipients, registered TPPs)

Data Inventory

Map the data the standard requires you to share against where that data lives in your systems:

Core banking system (accounts, balances, transactions)
Customer identity systems (name, contact details)
Product systems (product reference data, terms, fees)
Ancillary systems (cards, lending, insurance, energy metering)

This mapping exercise often reveals data quality issues — inconsistent formats, missing fields, or data spread across multiple systems. Identifying these early avoids surprises during integration.

Architecture Decision: Build vs. Buy

The biggest decision at this stage is whether to build your open banking API layer in-house or use a managed data provider platform. Key factors:

Factor	Build In-House	Managed Platform
Time to market	6–18 months	6–8 weeks
Ongoing maintenance	Dedicated team required	Handled by provider
Standards updates	Your responsibility	Provider keeps current
Security certification	Must achieve independently	Platform is pre-certified
Customisation	Full control	Configurable within platform
Total cost	Higher upfront + ongoing	Subscription-based

Most institutions — particularly those that aren't Tier 1 banks with large API engineering teams — choose a managed platform to reduce risk and time to market.

Phase 2: Architecture and Integration

API Architecture

Open banking APIs follow a layered architecture:

External API layer — standards-compliant REST APIs that third parties interact with. Endpoints, request/response formats, and error handling follow the published specification (Consumer Data Standards, FDX, UK OB Standard, etc.).
Authorisation layer — handles authentication, token issuance, and consent enforcement. Built on OAuth 2.0 with FAPI security extensions.
Data mapping layer — transforms data from your internal systems into the standardised response format. This is where most of the integration work happens.
Core system connectors — connections to your core banking system, identity platform, and any other source systems.

If you're using a managed platform, the external API layer and authorisation layer come pre-built. Your implementation work focuses on the data mapping and core system connectors.

Core Banking Integration

The integration between the data provider platform and your core banking system is the most critical technical component. Common approaches:

Direct database integration — read directly from the core banking database. Fast to implement but creates coupling and may impact core system performance.
API integration — connect through your core banking system's existing APIs. Cleaner architecture but depends on the availability and completeness of internal APIs.
Event-driven / data pipeline — replicate relevant data to a purpose-built data store that serves open banking requests. Adds latency but isolates the core system from external traffic.

The right approach depends on your core banking system's capabilities, performance characteristics, and your institution's architecture standards. Most managed platforms support multiple integration patterns.

Identity and Authentication

Your data provider implementation needs to integrate with your existing customer authentication systems. When a customer consents to data sharing, they authenticate through your institution's login — the same credentials and MFA they use for online banking. This means:

Integration with your identity management platform (Active Directory, LDAP, or identity-as-a-service)
Support for your existing MFA methods (SMS OTP, authenticator app, biometric)
Session management that aligns with your security policies

Phase 3: Consent and Consumer Experience

Consent Flow Design

The consent screen is the most consumer-visible part of your open banking implementation. Design considerations:

Clarity — use plain language to describe what data will be shared and with whom
Account selection — let consumers choose which accounts to share, rather than defaulting to all
Duration visibility — clearly show how long the consent will last
Branding — the consent screen should look and feel like part of your institution's digital experience
Mobile-first — many consumers will encounter consent flows on mobile devices

Consumer Dashboard

Build (or configure) a dashboard that lets consumers view and manage their active data-sharing consents. This is typically accessible from within online banking and should show active consents, consent details, and a clear revocation option.

Phase 4: Testing and Certification

Conformance Testing

Most open banking regimes require data providers to pass conformance testing before going live. This verifies that your APIs conform to the published standard — correct endpoints, response formats, error handling, security implementation, and consent flows.

Conformance test suites are typically provided by the standards body or regulatory authority. Run these early and often during development — don't wait until the end.

Integration Testing with Third Parties

Before going live, test your implementation with real third parties in a sandbox or pre-production environment. This catches issues that conformance testing misses — edge cases in data formatting, timeout handling, and consent flow usability.

Performance Testing

Open banking regulations often define minimum performance requirements — response time thresholds, availability targets, and concurrent request handling. Load test your implementation against these requirements, with margins for traffic growth.

Security Testing

Penetration testing and security review of the entire data provider stack — APIs, authentication, token handling, and data access controls. This should be performed by an independent security team, not the development team.

Phase 5: Go-Live and Operations

Registration

Register with the relevant regulatory authority as a data provider (ACCC in Australia, FCA in the UK, etc.). This typically involves submitting documentation about your implementation, security certifications, and compliance procedures.

Monitoring

Once live, continuous monitoring is essential:

API availability — uptime against SLA commitments (regulatory targets are typically 99.5%+)
Response latency — track p50, p95, and p99 response times against performance requirements
Error rates — monitor 4xx and 5xx error rates by endpoint and third party
Consent metrics — consent creation, usage, expiry, and revocation rates
Security events — failed authentication attempts, unusual access patterns, potential abuse

Standards Maintenance

Open banking standards are not static. The Consumer Data Standards in Australia publish regular version updates. FDX releases new API versions. PSD3 will replace PSD2 in Europe. Your implementation needs to evolve with the standards — either through in-house engineering effort or through a managed platform that handles updates for you.

Common Implementation Pitfalls

Underestimating data mapping. The gap between how your core system stores data and how the standard expects it in API responses is often larger than expected. Account types, transaction categories, and date formats all need transformation. Budget significant time for this.

Ignoring performance under load. Your core banking system may handle internal traffic well but struggle when thousands of third-party API requests hit it simultaneously. Design your architecture to isolate external API traffic from core system operations.

Treating consent as an afterthought. Consent management is often the last thing built but should be one of the first. Consumer testing of consent flows takes time, and poor consent UX directly impacts adoption.

Not planning for standards evolution. If you build a rigid implementation tied to the current version of the standard, you'll face significant rework when the next version is published. Build with flexibility in mind, or use a platform that handles version management.

Fiskil's Data Provider platform handles the API layer, security, consent management, and standards compliance — typically deploying in 6–8 weeks. Your team focuses on core banking integration while we handle the rest. Learn about our implementation approach.