Apache Spark
- Spark Daria - Essential Spark extensions and helper methods
- Spark Style Guide - By MrPowers
- Spark Fast Tests - helpers that work with Scalatest, uTest, and MUnit
Other
- Kotlin dataframe
- Duckdb - an in-process SQL OLAP database management system
- It also works great as a batch-oriented data transformation engine
- Harlequin - SQL IDE in your Terminal
- Works with DuckDB specifically