Does Kraken have a monthly fee?

I'm curious to know if Kraken, the popular cryptocurrency exchange platform, imposes any monthly fees on its users. As a frequent trader in the crypto space, I'm always looking to minimize my costs and maximize my profits. Do they charge a flat rate each month, or is it based on the volume of trades I make? It would be great to have clarity on this matter so I can make an informed decision about whether Kraken is the right platform for me.