Kettle

Kettle is a powerful, open source, metadata-driven ETL tool

License: GNU General Public License (GPL)

Used for

Data warehouse population with built-in support for slowly changing dimensions, junk dimensions and much, much more.
Export of database(s) to text-file(s) or other databases
Import of data into databases, ranging from text-files to excel sheets
Data migration between database applications
Exploration of data in existing databases. (tables, views, synonyms, )
Information enrichment by looking up data in various information stores (databases, text-files, excel sheets, )
Data cleaning by applying complex conditions in data transformations
Application integration