ETL using Python

Yes. Just write Python using a DB-API interface to your database.

Most ETL programs provide fancy "high-level languages" or drag-and-drop GUI's that don't help much.

Python is just as expressive and just as easy to work with.

Eschew obfuscation. Just use plain-old Python.

We do it every day and we're very, very pleased with the results. It's simple, clear and effective.

You can use pyodbc a library python provides to extract data from various Database Sources. And than use pandas dataframes to manipulate and clean the data as per the organizational needs. And than pyodbc to load it to your data warehouse.