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Zalando Search API¶
Identity¶
Search API is the lightweight presentation layer immediately above Base Search (the Elasticsearch cluster) in Zalando's catalog-search substrate.
"The Base Search Elasticsearch cluster itself is wrapped by a lightweight Search API component — another presentation layer." (Source: sources/2025-12-16-zalando-the-day-our-own-queries-dosed-us-inside-zalando-search.)
Its defining role is enrichment + sponsored-content blending — Base Search returns organic ranking candidates; Search API integrates two sidecars to produce the blended, personalised, monetised result set the rest of the stack consumes.
Sidecar integrations¶
- Algorithm Gateway — "enriches results with user actions data and re-ranked using the rules engine and our personalization and relevance ML models." This is the personalisation + rules-engine application point.
- Promotions Bidding Service — "it blends sponsored content with organic results." This is the monetisation application point — sponsored placements reach the right user at the right moment.
A search's result set therefore goes: organic candidates from Base Search → re-ranked by Algorithm Gateway → sponsored-blended by Promotions Bidding → handed up to NER / Catalog API for presentation.
Role as a control-plane lever¶
Along with Catalog API, Search API is one of the two presentation layers Zalando's Search & Browse team uses as a control plane for downstream load. During incidents, operators can:
- Reduce parallel-queries-per-request.
- Sample fewer requests into heavier ML model integrations (via Algorithm Gateway).
- Sample fewer requests into promotion-enrichment flows (via Promotions Bidding).
- Fall back to simpler ranking where needed.
These levers are the app-side half of the 2025-12-16 5-lever load-shedding cocktail.
Seen in¶
- sources/2025-12-16-zalando-the-day-our-own-queries-dosed-us-inside-zalando-search — canonical wiki instance.