# Vespa Schema Authoring

> Vespa .sd schemas — fields, tensors/HNSW, rank profiles

**Subcategory:** Vespa  
**License:** Apache-2.0  
**Source:** https://github.com/vespa-engine/skills/blob/65b9ae3/schema-authoring/SKILL.md

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## When it is useful

Writing, validating and evolving Vespa .sd schema files: field types, indexing pipelines, match modes, tensors and HNSW, rank profiles, structs, fieldsets, common pitfalls.

## The Catch

Apache-2.0 from the repo LICENSE; SKILL.md declares none. Engine is Apache-2.0 and free to self-host forever; Vespa Cloud is a free trial only ($300 credits, no card, app stops when credits run out) — not forever-$0 Cloud. Vespa-specific .sd grammar — not Elasticsearch mappings. Schema changes can require reindexing; verify with deploy validation.