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Zalando Fashion Store API (FSA)¶

What it is¶

The Fashion Store API (FSA) is Zalando's production deployment of the Unified Backend-For-Frontends (UBFF) GraphQL schema for zalando.com. It is the GraphQL aggregator that every page on the Zalando web and app consumes: the Rendering Engine — the runtime of the Interface Framework — issues GraphQL queries to FSA for each UI component's data, and FSA fans those out across Zalando's internal microservices and aggregates the responses (Source: sources/2021-03-03-zalando-how-we-use-graphql-at-europes-largest-fashion-e-commerce-company).

FSA's defining architectural property is that it consults only Zalando-operated APIs — third-party integrations are wrapped by internal proxy services first (e.g. the Contentful proxy for the Landing Pages stack), so FSA itself never becomes a direct runtime dependency of an external vendor (patterns/proxy-layer-for-external-saas; Source: sources/2022-09-28-zalando-more-editorial-content-please).

Relationship to UBFF¶

Where systems/zalando-graphql-ubff is the architecture (a single-service unified-graph BFF across 12+ domains running on in-house systems/graphql-jit), FSA is the name of the production instance behind the Fashion Store — the customer-facing surface of zalando.com. Earlier Zalando posts use "Fashion Store API" and "the UBFF" somewhat interchangeably; on this wiki, FSA is the concrete deployment and UBFF is the architectural pattern and schema.

Architectural role¶

  Web client / App client
            │
            ▼
  [Rendering Engine](<./zalando-rendering-engine.md>)  — walks entity tree,
                                     issues GraphQL per renderer
            │
            ▼
           FSA  — GraphQL aggregator
            │
            ├──→ product service
            ├──→ catalog service
            ├──→ cart / checkout service
            ├──→ recommendations
            ├──→ [Contentful proxy](<./zalando-content-proxy.md>)
            │      └─→ [systems/contentful](<./contentful.md>)  (external SaaS,
            │           isolated behind the proxy)
            └──→ dozens of other internal services

Design disciplines¶

No business logic in FSA — FSA is platform- and domain-agnostic; business logic lives in the downstream presentation-layer backends.
Zalando-operated downstreams only — third-party APIs are wrapped by internal proxies first. The Contentful proxy is the canonical example.
Per-platform deployment bulkhead via UBFF-level discipline — separate Web and App deployments of the same service, so a mobile regression cannot block the web release train (patterns/per-platform-deployment-bulkhead).
Persisted queries in production — FSA rejects raw GraphQL in production and accepts only registered persisted-query IDs (see concepts/graphql-persisted-queries).

Seen in¶

sources/2021-03-03-zalando-how-we-use-graphql-at-europes-largest-fashion-e-commerce-company — introduces FSA under its UBFF framing.
sources/2021-03-10-zalando-micro-frontends-from-fragments-to-renderers-part-1 — frames FSA as Interface Framework's data aggregation tier.
sources/2022-09-28-zalando-more-editorial-content-please — canonicalises FSA's "aggregation layer calls only Zalando-operated APIs" isolation discipline, realised for the Landing Pages stack via the Contentful proxy.
sources/2023-06-25-zalando-context-based-experience-in-zalando — FSA becomes the transport for request-scoped Experience context. When the Rendering Engine issues child-renderer queries, the resolved Experience name travels as an explicit query parameter; FSA passes it to the owning domain backend (Catalog / Product / Search), which applies the Experience's policies when shaping the response. FSA itself does not evaluate selection rules or pick the Experience — that is owned by the domain backend closest to root-entity resolution. FSA's role is consistent with no business logic in the aggregator: Experience-awareness is a transport concern, not a rules-evaluation concern. Canonical wiki instance of patterns/request-state-propagated-experience.