Data Cleaning

OpenRefine – A powerful tool for working with messy data: cleaning it, transforming it from one format into another, and extending it with web services and external data. [Free]

Talend Data Preparation – A data cleaning tool similar to OpenRefine that has some extra features, such as greater auto-detection of data types and useful functions, but can be more complex to use. There are both free and paid versions available. [Free]