Cathrine Wilhelmsen lists five interesting online tools:
When I need to quickly create smaller sets of test data or dummy data, I use Mockaroo. It is highly configurable with over 140 built-in field types for locations, personal information, product information, technical information and much more. Every field type can be customized, and you can also use your own regular expression to generate data. The data can then be exported to CSV, JSON, SQL, and Excel formats. The interface is simple to use and understand, and you can save your schemas and data sets for later reuse.
I’m fond of Coblis and was aware of the last two, but the first two were new to me.