Grumpy Finance produces its own wallet software that is available for download on its website, which allows you to store Grumpy Finance on your computer. For maximum security, you can store your cryptocurrencies on a dedicated hardware wallet such as a TREZOR wallet or a Ledger Nano X. If you do not wish to buy a hardware wallet, you may consider using a mobile wallet such as Atomic Wallet, Jaxx, or Coinomi to store multiple cryptocurrencies with some added security benefits.