Written by Paul Brown | Last updated 17.11.2025 | 13 minute read
Fintech consultancies now sit at the centre of Europe’s payment modernisation, translating complex regulation into production-ready platforms. PSD2 and Open Banking have moved well beyond one-off compliance projects; they have reshaped how banks expose data, authenticate customers and collaborate with third-party providers. Firms that treat compliance as a narrow legal hurdle tend to produce brittle, expensive integrations that are hard to extend. Those that treat it as an engineering discipline can unlock reusable components, faster product launches and competitive differentiation.
For consultancies, the challenge is to bridge three worlds at once: evolving regulatory expectations, legacy banking estates, and modern API-driven architectures. That means understanding the letter and spirit of PSD2, mastering standards such as the Regulatory Technical Standards (RTS) on Strong Customer Authentication (SCA) and secure communication, and keeping pace with UK Open Banking and emerging standards such as Open Banking Standard v4.0. In practice, effective PSD2/Open Banking compliance engineering is not just about avoiding enforcement action; it is about building a strategic platform for future open finance and, ultimately, PSD3.
A robust consultancy strategy starts with a clear, engineering-friendly model of what PSD2 and Open Banking actually require. PSD2 is a European directive governing payment services, customer protection and competition; Open Banking, particularly in the UK, is a regulatory-driven implementation of those principles through standardised APIs, security profiles and consent flows. While PSD2 defines broad obligations and RTS guidance defines principles for SCA and secure communication, Open Banking frameworks go further by standardising data models, endpoints and security profiles, often adopting API security profiles built on OAuth 2.0 and OpenID Connect.
From a consultancy perspective, the key is to reframe the legal and policy language into a set of verifiable engineering constraints and capabilities. Instead of simply listing “must apply SCA” or “must provide a dedicated interface for third-party providers,” a compliance engineering approach defines these as testable behaviours: how many independent factors are enforced, which exemptions are implemented, how consent is represented in data models, what uptime and latency constraints apply to APIs, and how fall-back mechanisms are controlled and monitored. This translation from regulation to executable requirements is where experienced fintech consultancies create disproportionate value.
Another crucial distinction is between the roles and obligations of different actors. Account-servicing payment service providers (ASPSPs) – typically banks – must expose interfaces for account information and payment initiation, while third-party providers (TPPs) such as AISPs and PISPs must securely consume them, identify themselves using qualified certificates and respect consent boundaries. Consultancies that support both sides of this ecosystem need a dual perspective: helping ASPSPs design robust, standards-compliant APIs and helping TPPs build resilient, multi-bank integration layers. This duality is essential for anticipating integration friction and designing for real-world interoperability rather than idealised standards.
Finally, compliance engineering has to account for the wider regulatory context beyond PSD2 itself. Supervisory authorities increasingly link payment security with ICT and operational resilience, including guidelines on ICT and security risk management, cloud outsourcing and broader frameworks such as the Digital Operational Resilience Act (DORA). A consultancy that isolates PSD2 from this wider risk landscape may technically pass audits but will leave clients exposed to supervisory findings around governance, outsourcing and resilience.
One of the most powerful contributions a fintech consultancy can make is to define a reference architecture where compliance is built into the structure, not bolted on via tactical patches. For many banks, the initial PSD2 response was to wrap legacy channels with thin API layers. That approach often satisfies a first regulatory deadline but leads to fragile, hard-to-maintain solutions. A consultancy-driven architecture should instead centre on clear separation of concerns: API exposure, consent and identity, payment orchestration, and integration with core banking systems.
A common pattern is to introduce a dedicated open banking gateway, either as a specialised deployment of an API gateway or as a broader access-to-accounts platform. This gateway terminates external connections, enforces OAuth/FAPI-style security flows, validates certificates, and routes calls to internal services. Beneath that layer, microservices or domain-oriented services handle account information, payment initiation, confirmation of funds, and consent lifecycle management. The consultancy’s job is to ensure that boundaries between these services align with both regulatory obligations and business domains, avoiding monolithic “PSD2 services” that mix concerns and slow change.
To make this architecture sustainable, consultancies should encourage clients to embed compliance controls as reusable platform capabilities rather than bespoke implementations in each service. For example, SCA flows should be treated as a core platform capability, available via well-defined APIs and configurable per channel and product, rather than being re-implemented in every payment journey. Similarly, consent management and customer communication (for example, informing customers when a new TPP is authorised or when access expires) should be centralised, with strong audit and reporting features that support both compliance and customer experience.
This is where clear architectural building blocks become invaluable. Consultancies can accelerate delivery and de-risk compliance by defining a standard set of components such as:
Beyond the high-level blueprint, consultancies must also engineer for practical constraints: rate-limiting and throttling policies that protect core systems while still meeting regulatory expectations for uptime and non-discrimination; error handling models that align with Open Banking standards; and fall-back mechanisms where allowed, while carefully avoiding screen-scraping practices that regulators are actively discouraging.
Finally, architecture work has to think several years ahead. PSD2/Open Banking APIs are not static; standards bodies and implementation entities continue to release new versions that update security and messaging design and introduce enhancements to data flows. A consultancy that bakes this evolution into the architecture – via strong versioning strategies, backward-compatible changes, feature toggles and consumer-driven contracts – enables clients to adopt new features with minimal disruption, rather than running recurring “big bang” migration programmes.
Strong Customer Authentication is where regulatory expectations, user experience and security engineering collide most visibly. PSD2 requires multi-factor authentication using independent elements, with dynamic linking between authentication codes, the amount and the payee for remote electronic payments. At the same time, guidance allows exemptions for low-risk and low-value transactions, and supervisors expect firms to implement robust transaction monitoring and fraud controls rather than blindly challenging every payment. Effective consultancies therefore treat SCA not as a static rule, but as a flexible risk engine.
This risk-based perspective reshapes the engineering challenges. Instead of a simple “always 2FA” model, consultancies design adaptable SCA orchestration services that can apply different factors (device binding, possession tokens, behavioural biometrics, step-up one-time passwords, or app-based approvals) depending on risk signals and exemption rules. Integration with 3D Secure for card payments, support for delegated authentication schemes, and alignment with Open Banking security profiles all need to be co-ordinated so that customers experience coherent flows rather than a patchwork of inconsistent challenges. Behind the scenes, careful key management, certificate lifecycle management and secure implementation of signing algorithms are essential to avoid undermining the integrity of dynamic linking.
From a compliance engineering standpoint, the SCA challenge is as much about evidence as about control. Regulators and auditors increasingly expect firms to demonstrate how SCA decisions are made, logged and monitored, and to show how exemption thresholds and risk models are validated over time. Consultancies can add real value by designing observability into SCA implementations: structured logging of risk scores and exemption decisions, dashboards that track challenge rates versus fraud rates by segment, and alerting for anomalous patterns such as sudden drops in challenge rates or persistent failures in critical SCA components. Over time, these data-driven insights allow clients to fine-tune SCA, reducing friction while staying well within regulatory expectations.
Because SCA and secure communication sit at the heart of PSD2, security must run end-to-end through the development lifecycle. That implies secure coding standards aligned with the chosen security profile, threat modelling focused on open API abuse and TPP impersonation, automated security testing for OAuth/OpenID flows, and disciplined handling of secrets and certificates in CI/CD pipelines. Fintech consultancies that bring security engineers into early discovery and solution design – not merely into end-stage penetration testing – are better placed to deliver platforms that are both compliant and resilient.
Even the best technical design can be undermined if governance and outsourcing arrangements are weak. Regulators now tie PSD2 compliance closely to broader ICT and outsourcing frameworks, including guidelines on risk management, cloud outsourcing and newer operational resilience expectations. For consultancies, this means the compliance engineering strategy must extend beyond code and infrastructure to encompass processes, documentation and third-party relationships.
A central challenge is the heavy reliance on vendors in most PSD2/Open Banking programmes. Banks and fintechs commonly adopt API management platforms, consent and identity providers, cloud infrastructure, fraud-analytics engines and monitoring tools from third parties. Each of these relationships may qualify as outsourcing of critical or important functions, which brings with it stringent requirements for risk assessment, contractual clauses, data-location controls, exit strategies and ongoing oversight. Consulting teams must therefore work closely with legal, procurement and risk functions to ensure that technology choices and operating models are compatible with regulatory expectations from the outset.
To make that practical rather than bureaucratic, consultancies can introduce a standard governance toolkit for PSD2/Open Banking initiatives. This might include:
Governance is not solely about risk mitigation; it also shapes the agility of compliance engineering. Poorly defined approval processes for changes to security configurations, API scopes or monitoring rules can add weeks to implementation timelines. Consultancies can help by designing streamlined, risk-proportionate governance workflows and embedding them into DevSecOps pipelines and tooling. That might include pre-approved configuration patterns for low-risk changes, gated workflows for high-impact alterations such as new data-sharing scopes, and integrated policy-as-code checks that prevent non-compliant deployments from reaching production.
Cloud strategy is another area where consultancies can provide both technical and regulatory alignment. Many banks seek the scalability and flexibility of cloud-native architectures for open banking workloads, but supervisors remain keenly focused on concentration risk, data-protection safeguards and exit planning. The consultancy’s role is to design cloud-native architectures that respect data-segregation policies, support robust encryption and key-management models, and provide transparent observability and audit trails. Linking infrastructure-as-code, configuration management and risk registers enables clients to show regulators not just that they have controls on paper, but that those controls are consistently implemented and monitored.
Ultimately, consultancies that treat governance and outsourcing as first-class elements of PSD2/Open Banking compliance engineering – rather than as an afterthought – help clients avoid costly remediation following supervisory reviews. They also create the conditions for faster, safer innovation, because the pathways for adopting new technologies and partners are clear, repeatable and compliant.
PSD2 and Open Banking created an initial wave of compliance projects that were often delivered under intense time pressure and framed purely around regulatory deadlines. The next phase is different. As markets move towards open finance and broader data-sharing regimes, firms need platforms that can support new business models, products and partnerships. This is where fintech consultancies can reposition PSD2/Open Banking work from a sunk cost into a growth enabler.
One way to do this is by designing compliance capabilities as reusable assets across the client’s technology estate. SCA orchestration, consent management, API security and monitoring should not be confined to regulatory APIs alone; they can underpin mobile banking apps, partner integrations, embedded finance offerings and data-sharing initiatives beyond payments. Consultancies that help clients generalise their PSD2 components into enterprise-wide platform capabilities create compounding returns: every new product can launch faster because the building blocks are already compliant, tested and integrated.
Another long-term value lever lies in data and analytics. PSD2/Open Banking platforms generate rich telemetry: API usage patterns by TPP and endpoint, SCA challenge rates, error codes, latency and uptime metrics, fraud signals and customer behaviour across channels. Consultancies can help clients turn this into actionable insight by layering data platforms and analytics on top of compliance-driven logging. For example, anomaly detection on API error patterns can highlight failing TPP integrations before they cause customer impact; analysis of SCA friction by segment can inform user-experience design and exemption tuning; monitoring of consent lifecycle events can reveal opportunities for proactive customer engagement.
The most forward-looking consultancies also engage with strategy teams to shape open banking product roadmaps. That might involve exploring premium APIs offering richer data or faster payment capabilities to trusted partners, designing white-labelled services for fintechs, or supporting ecosystem propositions where the bank acts as a platform for third-party innovation. Because compliance engineering gives them deep insight into the technical limits and opportunities of the platform, these consultancies are well placed to advise on which propositions are feasible, how they should be priced and how they can be governed without triggering concerns around discrimination or unfair treatment of TPPs.
Capability building is equally important. If the client’s own engineering, risk and product teams remain dependent on external consultants for every change, the platform will struggle to evolve at the pace of regulation and competition. Effective consultancies therefore embed training, pair-programming, architecture clinics and coaching into their engagements. They help clients establish internal standards for open API design, security patterns and change management, and they support the creation of cross-functional squads that own open banking journeys end-to-end. Over time, the consultancy’s role can shift from delivery to assurance and innovation partnership.
Finally, lasting value comes from anticipating regulatory evolution rather than merely reacting to it. Discussions around future payment regulation, open finance and cross-sector data sharing indicate that upcoming frameworks will deepen and broaden today’s obligations rather than replace them entirely. Consultancies that keep clients informed about emerging regulatory themes can steer platform design decisions in ways that avoid regret later. Architectural flexibility, clean domain boundaries, well-documented APIs and strong observability are all hedges against regulatory uncertainty.
In summary, fintech consultancy strategies for PSD2 and Open Banking compliance engineering must weave together regulation, architecture, security, governance and business strategy. The consultancies that add the most value are those that can translate complex rules into robust, testable engineering patterns; design platforms that make compliant behaviour the easiest path; build governance and outsourcing frameworks that support rather than stifle innovation; and help clients leverage their compliance investments as foundations for open finance growth. Rather than seeing PSD2/Open Banking as a one-off hurdle, they treat it as the blueprint for a new, interoperable financial ecosystem – and they engineer accordingly.
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