dbt (data build tool)
SQL-based transformation tool — writes the T-step of ELT as modular SELECT statements with Jinja templating, dependency graphs and tests.
Tristan Handy / Fishtown Analytics, 2016 (now dbt Labs). A dbt model is a SQL statement materialised as a view or table. The ref() macro builds the DAG. Built in: schema tests, snapshots (SCD type 2), documentation, lineage visualisation.
Defined the role of "analytics engineer". dbt Cloud = managed. dbt Core = open source. Competitors: SQLMesh (newer, stronger semantics), Dataform (Google). Standard in modern ELT stacks (Snowflake/BigQuery/Redshift + dbt + BI).