OpenRefine is a free, open-source tool for tidying messy data. You use it in your web browser, but it runs locally on your own computer as a Java application. Facets let you filter large datasets and apply operations to the filtered view. Clustering merges similar values to fix inconsistencies. Reconciliation matches your data against external databases. Operations can be undone and replayed on a different version of the data. You can convert data between formats, enrich it using web services and contribute to Wikidata and other Wikibase instances.
According to the project, your data is cleaned on your own machine, with no vendor cloud service involved. The software is released under the BSD licence. The project is maintained by a small core team and relies on grants and community support. Since 2020 it has been fiscally sponsored by Code for Science & Society, a US non-profit; there is no controlling company. For a European organisation this means processing stays entirely under its own control.