Bip39. First and foremost you must retail store it SEPARATELY from the seed. Having your seed and your passphrase in a similar place defeats the goal of having a passphrase in the first place. No, there is not any technical limit for the size of your respective passphrase. On the https://bookmarkbells.com/story18703645/bip39-mnemonic-https-linktr-ee-bip39-a-simple-key-for-bip39-unveiled