Does GDS mandate REST for all government digital services?

GDS API design guidance (published on gov.uk) recommends REST + OpenAPI 3.0 for all government APIs. GDS Service Standard assessment criteria include: API documentation is machine-readable (OpenAPI satisfies this), APIs are designed for reuse (REST's standard conventions facilitate this). GDS does not explicitly prohibit GraphQL but the GOV.UK API catalogue and all published GOV.UK APIs use REST. ClickMasters uses REST for all GDS-assessed services.

When is GraphQL a genuine improvement over REST in UK projects?

GraphQL genuinely improves developer productivity when: a dashboard requires data from 5+ REST endpoints per page load (multiple round trips add 200–500ms per endpoint), mobile clients need to minimise payload size (useful on 3G connections for UK users in rural areas), and your frontend team iterates faster than your API team (new fields in the schema without new endpoints). These benefits are real but apply to a minority of UK projects — most benefit more from well-designed REST.

Rest Vs Graphql Vs Grpc Api Design Uk

REST vs GraphQL vs gRPC — UK API Architecture Decision Framework (2025)

Updated: August 20259 min read

🇬🇧 UK💷 GBP📊 Comparison🔒 UK GDPR⚖️ UK Law

Direct Answer

REST with OpenAPI 3.0 is the standard for UK external APIs — required for FCA COBS machine-readable disclosure, NHS FHIR R4 compliance (FHIR is a REST standard), and GOV.UK API design (GDS mandates REST). GraphQL for complex internal data requirements where over-fetching is a genuine problem. gRPC for internal high-performance microservice communication. The decision is not REST vs GraphQL vs gRPC — all three have distinct roles in a well-designed UK system. API design decisions in UK regulated software carry compliance implications. Here is a concise decision framework focused on UK-specific requirements.

Use Case	Recommended API	Reason
External API (customer-facing, partner)	REST + OpenAPI 3.0	FCA COBS disclosure, NHS FHIR compliance, GDS API standards
NHS FHIR R4 integration	REST (FHIR R4 spec)	FHIR IS a REST standard — GraphQL cannot substitute for FHIR
Open Banking (PSD2)	REST (OBIE standard)	Open Banking Implementation Entity mandates REST
Complex dashboard data (many sources)	GraphQL	Reduce over-fetching — one query vs multiple REST calls
Internal microservice communication	gRPC	Binary protocol — low latency, streaming, strong typing
GOV.UK API (GDS Service Standard)	REST + OpenAPI 3.0	GDS API design guidance mandates REST + OpenAPI
Mobile app with bandwidth constraints	GraphQL or REST (careful field selection)	Request exactly the fields needed per view
Real-time streaming data	gRPC (bidirectional streaming)	HTTP/2 streaming — lower overhead than WebSocket for binary