ACCELERATOR · BLUEPRINTS

API & Microservices

Design, build and govern APIs and microservices that are consistent, secure and ready for regulated environments.

The API & Microservices blueprint establishes the standards, patterns and infrastructure for building well-governed service-oriented systems in financial services. It covers API design conventions, service communication patterns, contract testing strategies, API gateway configuration and versioning policies, providing the consistency layer that enables autonomous teams to deliver independently without diverging into incompatible implementations.

provenAvailable

Key Features

API Design Standards and Style Guide

Opinionated conventions for REST and gRPC API design covering resource naming, error handling, pagination, filtering and versioning, aligned with Open Banking and ISO 20022 interface expectations.

Service Communication Patterns

Reference implementations for synchronous (request-response), asynchronous (event-driven) and hybrid communication, with guidance on when each is appropriate in payment, lending and compliance flows.

Contract Testing Framework

Consumer-driven contract testing setup using Pact or similar tooling, integrated into CI pipelines to catch breaking interface changes before they reach shared environments.

API Gateway and Security Baseline

Gateway configuration patterns for rate limiting, OAuth 2.0 / mTLS enforcement, request validation and audit logging, meeting the security expectations of financial services API exposure.

Use Cases

Open Banking API Layer

Banking

Designing and implementing PSD2-compliant Open Banking APIs with consent management, strong customer authentication integration and TPP onboarding workflows.

Internal Payments API Platform

Payments

Building a consistent internal API layer across payment initiation, clearing, settlement and reconciliation services to replace point-to-point integrations between legacy systems.

Risk and Compliance Service Mesh

Lending

Decomposing a monolithic risk engine into independently deployable microservices for credit scoring, affordability calculation and policy evaluation with well-defined API contracts.

Technical Stack

Kotlin / Java (Spring Boot)TypeScript (Node.js / NestJS)gRPC / Protocol BuffersKong / Apigee (API Gateway)Pact (Contract Testing)OpenAPI 3.1

Deliverables

  • →
    API Design Style Guide(Reference document)
  • →
    Microservice Reference Implementation(Code repository)
  • →
    Contract Testing Pipeline Configuration(CI/CD configuration)
  • →
    API Gateway Security Baseline(Infrastructure-as-code)

Expected Programme Outcomes

Time

8–12 weeks

saved on API standards setup

Risk & Compliance

90%+

interface consistency across services

Cost

4–6 months

of integration rework avoided

Quality

95%+

across all service teams

Prerequisites

  • →Service boundaries identified (see Domain-Driven Design blueprint)
  • →Cloud infrastructure and Kubernetes cluster available
  • →Authentication and identity provider selected

Proven in

Case studies that used this accelerator.

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