Bip39 Online. First and foremost you should keep it SEPARATELY from your seed. Possessing your seed and your passphrase in the same site defeats the objective of aquiring a passphrase to begin with. Any individual else who discovers the phrase can steal the bitcoins. It should be saved magic formula, https://mixbookmark.com/story4177037/bip39-words-https-linktr-ee-bip39-bip39-wallet-can-be-fun-for-anyone