Apache Arrow defines a language-independent columnar memory format for flat and nested data, and provides libraries that implement it in languages including C++, Java, Python, Go, Rust and R. Data systems use it to exchange data without serialisation overhead and to run analytical operations in memory. Arrow is a building block rather than a standalone platform: engines and tools embed it. It is licensed under the Apache License 2.0.
The project is developed under the Apache Software Foundation, a US 501(c)(3) non-profit, so US law frames the project's governance. Arrow does not store data itself, so the sovereignty question sits with the systems that embed it. For a European organisation, Arrow matters as an open, community-governed format: a dataset written in Arrow can be read by different engines, which reduces dependence on any single commercial product.