BIP39 to Decred Seed
It supports the use of password-derived BIP39 seeds.
Due to how Decred seeds currently work, the resulting hex seed has double the size of standard decred seeds (33 word mnemonic seeds), therefore it's not currently possible to generate them (the mnemonics based on the PGP wordlist) from the BIP39 source seed.
Go 1.12+ with modules support required.
git clone https://github.com/matheusd/bip39-to-dcr-seed cd bip39-to-dcr-seed go run . --help