Here are some options, each with its own nuance:
Closest sounding options:
* Casside: This is the most phonetically similar to "Kassidy" and may be the best option if you're looking for something that sounds familiar.
* Cassidy: This spelling, which is common in English, is also a reasonable choice and might be easier for French speakers to recognize.
Other options:
* Cassie: A common nickname for Kassidy, this option might work well if you want something short and simple.
* Cassy: Another nickname option, but it's not as common as Cassie.
Using a related name:
* Catherine: This name has a similar feel to Kassidy, though it's not as close in sound. It could be a good option if you're looking for a more traditional French name.
Ultimately, the best option depends on the context and what you're trying to achieve. If you're simply looking for a way to say "Kassidy" in French, then "Casside" or "Cassidy" are probably the best choices. However, if you're trying to find a more culturally appropriate name, then you might want to consider using one of the other options.