# Evidence USQL / Query Layer

**Canonical:** https://apis.io/apis/evidence-dev/usql-query-layer/  
**Provider:** Evidence — https://apis.io/providers/evidence-dev/  
**Documentation:** https://evidence.dev/universal-sql

Evidence USQL / Query Layer is one of 3 APIs that [Evidence](https://apis.io/providers/evidence-dev/) publishes on the [APIs.io](https://apis.io/) network, described by a machine-readable OpenAPI specification. Tagged areas include USQL, DuckDB, Query Engine, and Parquet. The published artifact set on APIs.io includes API documentation, an API reference, and an OpenAPI specification.

Universal SQL, the query engine built into Evidence core and powered by DuckDB's WebAssembly distribution. It extracts data sources to Parquet and lets you query across multiple sources with a single SQL dialect via an open data-source-adapter standard. Consumed in-process through SQL, not via a network REST endpoint.

## Machine-readable artifacts (4)

- **Documentation** — https://evidence.dev/universal-sql
- **APIReference** — https://docs.evidence.dev/core-concepts/data-sources/duckdb
- **GitHub** — https://github.com/evidence-dev/evidence
- **OpenAPI** — https://raw.githubusercontent.com/api-evangelist/evidence-dev/refs/heads/main/openapi/_original/evidence-dev-openapi.yml

## Other Evidence APIs (2)

- [Evidence Framework (SQL + Markdown)](https://apis.io/apis/evidence-dev/evidence-framework/)
- [Evidence Cloud](https://apis.io/apis/evidence-dev/evidence-cloud/)

## Tags

USQL, DuckDB, Query Engine, Parquet

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Profiled by [API Evangelist](https://apievangelist.com) and published on [APIs.io](https://apis.io/apis/evidence-dev/usql-query-layer/). The API's provider profile, Kin Score and agent-readiness rating are at https://apis.io/providers/evidence-dev/.